Dead Water

Note: This walkthrough started with comments taken from the source data files for this campaign, which were based on Normal difficulty. Thus, scenario-specific notes which do not specifically mention a difficulty level are either of a general nature or should be assumed to refer to Normal.

Campaign Strategy

Recruitment and promotion

You have piercing-attack Mermen to fight pierce-resistant Undead. What to do?

Fortunately, for this campaign you are given access to a special impact-focused unit: the Merman Brawler, which is an advancement of Merman Citizen, the peasants of the Mermen. Spamming Citizens and promoting them to Brawler is one way to play the campaign; and Brawlers backed by leadership can be especially deadly. The Brawlers have a very interesting tail attacks with the stun effect: A unit hit by this attack loses its Zone-of-Control for the rest of the your turn. With the Undead's low impact resistance, this can allow for skirmishing attacks against an unsuspecting, vulnerable enemy unit, traversal of "roadblocks", or the positioning of units in better-defensible terrain. (Of course, moving behind the enemy line is dangerous, so don't go skirmishing irresponsibly.)

Alternatively, or in addition to Brawlers, you could focus on the vanilla Merman units which have non-pierce attacks: The Netcaster and the Priestess, and to a lesser extent, Enchantresses.

Netcasters are not immediately recruitable - you have to recruit Hunters, whose damage type is Pierce... you'll have to carefully, but decisively, build up their experience: When they level, not only does their damage type change to Impact (both for ranged and melee), but they also gain the *Slow* effect when attacking from a range, which is incredibly useful: It balances out the day/night cycle advantage of the Undead (damage per attack drops by 50%), as well as their movement advantage on land over the fishy Mermen (50% movement point drop).

A Priestes is useful already as its Level-1 precursor, the Merman Initiate, as its damage type is Pierce to begin with - and it's magical, so it is more likely to hit even Undead on land. Unsurprisingly, though, Initiates are even more fragile than Hunters, limiting this usefulness. Many scenarios benefit from having at least multiple healer units (for two battle hot-spots, for longer lines and for healing each other), so you should also promote an Initiate or two (or three) to Priestess early on, to supplement your starting Priestess, Cylanna. She's worth "investing" experience in for promotion to Diviner (Level 3), as which she provides the illumination effect. You can often combine Leadership and Illumination by their higher-ups "Inspecting the troops" from behind the battle line: Some leader and a Diviner move in; front-line unit attacks; leader and diviner move to next unit.

Fighters/Warriors and Spearmen are less useful in this campaign, but you will not always be fighting only Undead, so groom a few on your roster, "just in case". Also, magic in various forms may change a unit's damage type, and these units stand to benefit the most for such changes.

Other advice

You begin the campaign with two Loyal units, and additional ones will join you along the way. Try and make sure they survive... you must hang together or you will likely all hang separately. Or have your body parts eaten by corpses separately.
Very often, the choice of a good strategy for a scenario depends on the immediately succeeding scenario, so if you're already reading this walkthrough - you may want to read one scenario ahead.

Scenarios

Invasion!

Objective: Defeat the enemy leader.
Lose if: Kai Krellis or Cylanna die or turns run out.
Turns: 30/28/26/26 (easy/normal/hard/nightmare).
Starting units: Kai Krellis, Cylanna, Gwabbo and six citizens.

This scenario is tricky. Mastering a winning strategy may take you a few attempts; but ultimately, it's not as hard as it looks.

A key feature of this scenario is that when the Undead capture any village, Walking Corpses spawn. (Soulless spawn on Difficult.) In light of this, you have two possible strategies, with which players have had success:

General Motors (mass production). Your basic strategy should be to take and hold as many villages as possible, both to prevent the spawning and boost your income. If you don't let many villages fall into enemy hands, eventually your income and resulting troop churn-out will be overwhelming. First turn, recruit a mix of level 1's and Citizens. Send a couple level 1's south to capture and protect villages there and send the Citizens in all directions to snatch up villages. Concentrate on keeping Cylanna and Gwabbo safe; you can take tremendous losses of other units and still win. By day, swarm your Citizens around isolated enemy units, similar to Bats.
Blitzkrieg (leader assassination). On the first turn, recruit only (or mostly) Level-1 units, and move them South-East, carefully. When you see an opening to go for the enemy leader, advance and kill him. The enemy will be focused on capturing villages in order to create an overwhelming number of Walking Corpses - so much so that you may be able to just walk in and kill their leader.

You can also combine those two approaches somewhat, sending a semi-strong contingent South and then along the bottom of the board to the enemy leader, while most of the enemy's units are distracted up North.

You can let the swimming Soulless/WC advance a bit towards your keep, so that your baby king can dart out to get an easy kill or two. As Gwabbo hints, you would be wise to get Krellis as much experience as possible this scenario; it will make the next scenario much easier. It's also much easier to defend when you're sitting on villages, like those around your keep.

You should keep your Citizens and wounded safe from becoming Walking Corpses - which often means sitting them on villages, but you can think of other ways, like using the ZOC's of non-citizen units (the citizens are Level-0 and don't exert a ZOC) to protect them.

Bat control is essential. Initiates are good against Bats. A key to success is understanding how the Bats work: Often, bats will forego capturing a village in favor of making an attack; thus, if a Bat is close to making a village capture, try distracting it with some Citizen bait.

If you start losing villages, it may not be the end of the world. You can sacrifice the land villages, but hold the ones in the water, using a couple of Fighters/Hunters plus Citizens. Use Cylanna, Gwabbo, and a few Citizens to hold off the Skeletons and Soulless/WC Southeast of your keep until the village situation is under control. Remember to look for an easy path to the enemy leader, even if there are swarms of Walking Corpses elsewhere.

Towards the end, your income probably will be quite large, so if the situation is under control, then it's better to milk XP than go for an early finish. You can swarm the enemy keep with Citizens and take your time to end it. Try to get Krellis to level 1, while also turning some of the Citizens into Brawlers.

Flight

Objective: Either
- Move Kai Krellis to the north-west corner of the map. He must be level 1 or higher.
- Defeat all enemy leaders (different bonus for each).
Lose if: Kai Krellis or Cylanna die or turns run out.
Turns: 21/22/23/24 (easy/normal/hard/nightmare).
Starting units: Kai Krellis, Cylanna, Gwabbo (if he survived the previous scenario).

Hopefully Kai Krellis is at least half leveled up already. Otherwise, this can be painful, as one of the victory conditions is that the Kai must be at least level 1.

You must decide whether to attack east or southwest. To the east is the prospect of more experience, while to the southwest is an easier foe and less distance for Krellis to travel back to the signpost.

Option 1, east: Recruit a bunch of Citizens, Brawlers, and Initiates, and send them east with Krellis. Use Citizens to lure the Skeleton Archer types into the water. They are easy pickings there for other Citizens, Brawlers, and Krellis. One of those guys gets Krellis half way up to level one. A few Citizens should also survive to become Brawlers. Remember that you can often turn a near-dead Citizen into a healthy Brawler by going for a kill, especially with the leadership of Krellis if he is already at level 1. About the time you get Krellis leveled up, and you are thinking about retreating everyone else, the bats will arrive. On Difficult, this will be a nasty number of Blood Bats. Use Hunters and Initiates to clear a path back west. Send three or four expendable units with Krellis. Their job is only to serve as bat bait, distracting the bats from Krellis, so that he does not get ZOC-locked. Krellis runs for the corner, while the rest of the troops gain experience doing a fighting retreat from the skeletons and other bad guys arriving in the middle of the map. On the other hand, if you manage to kill the northeast leader, you can consider the alternative of heading south and then west, to kill the final two leaders for a total victory.

Option 2, southwest: Send Citizens east, while your best troops go southwest. After you advance to where you meet the enemy, you will start retreating almost as quickly, especially at night. Feed near-dead Blood Bats to Krellis for experience.

Whichever option you choose, this is not the normal sort of scenario where you necessarily will slaughter all the enemy. It suffices to get enough experience for Krellis to level up and then have him run like hell for the signpost. Ignore gold for now. You don't need much on the next level.

Killing all the enemy leaders will end the level, but that won't be easy. However, killing any enemy leader gives you a nice reward so you should consider defeating as many leaders as you can manage. Each one gives you a different bonus: defeating Mal-Kevek grants you a loyal Dread Bat, defeating Mel Daveth gives you a loyal Vampire Bat and a ring of strength (+1 to all attacks and +3 hitpoints) and defeating the Dead Knight gives you a loyal Bat Corpse and 120 gold. Even if the enemy armies outnumber you greatly, when you manage to assassinate a leader, all of his troops will go down with him.

Wolf Coast

Objective: Defeat the enemy leader.
Lose if: Kai Krellis or Cylanna die or turns run out.
Turns: 18/17/16/16 (easy/normal/hard/nightmare).
Starting units: Kai Krellis, Cylanna, all loyal units available.

This is a fairly easy small level to give you a break - if you're careful.

In this level you're only going to be facing wolves, of all kinds and sorts, and quite a few of them. The (single) enemy, Gashnok, is a Level 3 Direwolf Rider, and he has plenty of underlings. On medium difficulty he'll recruit between two and three castles of six units, mixed L1 and L2.

You're following the coastline of the bay of Tirigaz (for some odd reason), so now you face North and land is to your East. The terrain, West to East, is mostly Deep Water -> Shallow Water -> Ford -> Sand -> various land tiles. So you like to fight in the West, and wolves like to fight in the East.

Easy peasy, right? They're after some Merfolk flesh, so you just lure them west into the water, where they're vulnerable, and make short work of them during the day. Except... it's a bit more complicated than that:

Most of the villages are on land - and you do need them (see below).
Land-based units actually _like_ fords - much better than sand. They'll get full movement speed and 40% instead of 30% defense. So you need to decide whether to fall back to the deep water - where you're really pressed to the edge and give up on villages - or try to maneuver so that you defend from the shallow-water-ford hexes, and form a line so that the wolves are stuck on the sand.
There's treasure in the East... a pond on the Eastern edge of the level has a Storm Trident sticking out into the air. And close to that pond, down South, you have a pair of wild Wolves which will not wait until turn 2 to be active, like the enemy recruits.

You should probably head north after recruiting about a castleful (in addition to your loyals). Try to lure some of the wolves towards you into the shallow water beyond the ford, but not all of them. If the wolves come in too big of a pack, you can split them up by sending Citizens (and a bat if you have one) off in another direction, not going too far but also being careful not to risk being overrun.

You really should have a second Priestess here, or level an Mermaid Initiate up immediately, if you haven't already. Leveling Netcasters and perhaps another Priestess and/or an Enchantress is also possible. You'll want a bunch of both.

When you can safely get to the Storm Trident pond (don't be too hastly), a fighter would be a wise choice of a bearer for it: They have high HP; this doesn't replace an existing (and invaluable) ranged attack for the unit; and you get to make "piercer-only" unit have another attack type which works well on the bony Undead. With the trident, your Fighter will level quickly; when you get him to Level 3, make him Triton, not a Hoplite: He will be more of a offensive than a defensive unit, plus - Tritons choose between a Pierce and a Blade melee attack, and Skeletons are a bit less resistant to blades.

Money is useful going into the next scenario, but it's hard to make a buck in this one... Scrounge every gold piece you can by starting with mostly level 1's (and 0's) and taking villages when you can manage it.

What about the prospect of rushing the enemy leader? This could be possible in theory, coming up North through the safer Western edge while the wolves are none the wiser. However, the experience gained on this level may be important (if you haven't fought your way through enemy leaders in the previous scenario).

scorchgeek: I actually had great success with a leader-rush tactic. I recalled a Spearman and an Enchantress and sent them Southeast to kill the wild Wolves, then recruited three citizens and also sent them in that direction. Then I recalled a couple more L2 units and sent them Northwest with the starting units to the very edge of the map. All of the wolves then charged South, whereupon I sacrificed the citizens (keeping them in the water to slow down the wolves) and sent the valuable units West, out of their reach. At this point I had three turns to sweep in and take out the leader before they could get back North (which occurs by turn 8), giving me a nice 285 gold to start the next scenario with. The only downsides were that I didn't get a chance to get the storm trident and that I had only 6 L2 and L3 units for the next scenario (but I did level nearly that many in the next scenario, as it was relatively easy with that amount of gold).

nuorc: I gave the trident to Krellis, although I had to be careful about the right timig so he didn't get chewed up. After that he had a ranged attack (unlike before), and he either killed enemies helping levelling him, or he softened up the opponent helping levelling my other units, both being great with the leadership ability.

Slavers

Objective: Defeat all enemy leaders.
Lose if: Kai Krellis or Cylanna die or turns run out.
Turns: 30/28/26/24 (easy/normal/hard/nightmare).
Starting units: Kai Krellis, Cylanna, all loyal units available.

You continue to travel North, with land to the east and safe, deep water to the west. Unlike the previous scenario, there isn't too much of that ford-like shelf near the shores - which works to your benefit. However, the terrain on land is mostly marshes and sandy shores - which is the ideal for your enemies here, the Saurians.

There are 3 enemy leaders - South, Middle and North - all Level 3 Flankers (= the skirmishers among the Saurians). They're slavers, with a slave population of mixed races (more on that later) - and your presence certainly stirs up trouble. So, they just have to try and kill you, I guess...

Three leaders, each recruiting more than two castle-fulls even on Medium, plus some starting guards, means about 40 units (on Medium), and with almost all of the terrain favorable to them, and the skirmishing - that's quite the infestation. The thing is, the individual units are all Skirmishers and Augurs (a mix of L1 and L2 - thus also Ambushers, Oracles and Soothsayers); they're relatively weak individually. But don't get tempted to start picking off one or two of them, since you'll promptly be overrun by the horde.

There are a few resources at your disposal to make things easier:

A free loyal Brawler - an escaped slave finds you at the beginning of this scenario who briefs you about the situation. Specifically, he tells you about...
A potential slave revolt: Once during this level, you can rouse the slaves to revolt. This will cause each slaver village to emit 2-4 L0 and L1 units, Mermen and outlaw-Humans, who will proceed to try and murder their evil captors. That's a rather silly strategy for a slave revolt, and in fact you'll just be using them as bait and cannon fodder, but, well, Cylanna and Gwabbo did say you are now an established leader, and that's what politicians do.
100 gold in a treasure chest in a shipwreck on a tiny island up north.

With this in mind, let's get to it...

Recruit/recall two castles (if you're short on gold) or three (if you can aford it), one of which should be all Level-2's. Hopefully that includes at least one more healer. Healers are essential in this scenario. Also, any units close to leveling are good recall choices. If you make it three castle-fulls, some citizens may be an economic choice: Saurians like to pick on them, and you won't regret their possible deaths that much.

Send a quick Citizen (or a non-undead Bat, if you have one) North to explore the shipwreck and get the Gold, as well as to tag the villages along the way; send everyone else east... but be careful - you start at Dusk. Hang back a bit during the first watch of the first night: Don't try to grab as much territory as possible; instead, try to lure the Saurians into the water.

As soon as the Saurians get within range of your troops, what you want to do is form a continuous line, defending against skirmisher infiltration - not move individual units to supposed safety or to plan an attack. Your ZoC are useless and within a turn they'll separate whatever "tank" unit you think you have from the others and hammer into you from all sides. The Ctrl+V key, displaying potential enemy moves, is your best friend in this scenario; use it, use it, and use it some more.

During daytime, be more aggressive in taking out the troops and getting to the Southern leader - but again, don't leave any units out and exposed, and try to maintain your line. At night, be conservative and forego attacks that would put your units at risk. As you're going further inland, note that forming a line on "your" side of a stream within the swamp puts the Saurians at a disadvantage: They will have to attack you from Shallow Water hexes, where their defense is only 40%, not the 60% you both have in a Swamp; so sometimes it's worth it forming a longer, somewhat winding line for that favorable terrain bonus. Also remember the Saurians surprising affinity for Sand.

For triggering the slave revolt, a good time seems to be turn 7, after you've concluded two days of attacks. It's dusk then, and almost all Saurian forces are either upon you or very close - and the slaves will distract them from that night's counter-attack, being effective in that capacity for at least two turns as the slavers divert their efforts to quell the revolt. Plus, this will slow down the rest of the Saurians coming from the North. Still, if you find you find yourself in a rough patch earlier than turn 7, don't hesitate to trigger the revolt right then.

There is a pair of prizes on this level, within cages near two of the slaver leaders' castles (South and North). They contains:

Keshan, a Drake Burner: He should be very useful over the course of your campaign
Siddry, a Human Poacher: He's not going to be much help here, and he won't come with you (so you can't recall him in future scenarios). If you keep him safely alive, he will come back eventually, in The Flaming Sword with some friends who are a big help taking villages in the beginning (and not much help thereafter).

When it's safe, rescue the Drake Burner, and try to get him some experience - but don't bank on him too much, and be extra-careful he's not targeted; he has lots of HP, but very poor resistance. When he advances, perhaps in a later scenario, make him a Flare, for the leadership bonus - as you will often have large hordes of low-level troops and only one other leader, Krellis (who also has to recruit initially).

After taking out the Southern leader and taking over the keep, and if you haven't recruited a third castle-full earlier - you could now recruit a few replacement units and some Citizens. As additional waves of the enemy arrive from up north, you may need to continue to maintain a disciplined line at a favorable location.

After that it should be no problem wiping out the other two leaders: If you have survived this far, you have quite a few high-level units; and they've got nothing left beyond the ability to recruit about a unit per turn. Advance cautiously, while keeping an eye on the clock.

Note: If you find you cannot beat the scenario, you may need to go back and replay the campaign to this point, concentrating on promoting units in each scenario and gathering more gold in the previous scenario.

Tirigaz

Objective: Destroy all the undead.
Bonus objective: Also kill Marg-Tonz (early finish bonus + 100 gold).
Lose if: Kai Krellis or Cylanna die or turns run out.
Turns: 18/17/16/16 (easy/normal/hard/nightmare).
Starting units: Kai Krellis, Cylanna, all loyal units available.

You've made it North across the bay of Tirigaz, and have arrived at a shipping harbor on its outskirts. The port-master is the tough, but fair, Marg-Tonz - an Orc Sovereign (Level 3); and several Orc Crossbowmen (on Medium) or Slurbows (on Hard) man fortified guard towers.

... but this is not what the level is about. You have been followed by a contigent of Mal-Ravanal's marine scouts, i.e. his more Ethereal minions: Ghosts, Wights, Shadows, Specters and Nightgaunts (the latter not on Medium) - a sizable pack. Luckily for you, they have no keep - it's just a intercept force. These are your proper enenmies here: The Orcs wont attack nor recruit as long as you stay out of their way.

The Undread are actually pretty easy here, so long as you give the higher-level ones their due respect, and maintain your solid line.

Don't go too negative on gold, but recruit three or four higher-level units. You want Priestesses/Diviners and Enchantresses/Sirens for their Arcane or Magical ranged attacks. A great unit here would be a melee-oriented one with a Storm Trident (a Triton would be particularly effective). Keshan, your newly-liberated Drake, can also help you - with fire attacks and being able to take some punishment. Do mind his limited mobility in Deep Water: You'll need to be careful not to block his path to actually making contact with the enemy; at the same time, don't leave him stranded. The Bats are less helpful than usual - weak during the day and vulnerable at night; don't over-expose them to danger.

As the Undead make their initial advance, don't rush in - wait until daytime to go after them, as you have plenty of time. Watch their ranges and place your line accordingly (a vertical line should do nicely).

When you've defeated the Undead you're presented with a choice: Be diplomatic and respectful, and just leave like you told their harbor-master you would; or you could be the ruthless Machiavellian leader and just slaughter him in a surprise attack and treat yourself to some of the port city's taxes (100 gold which he guards).

If you decide to go after the Orc leader (seeing how the extra gold comes in very useful in the following scenario), wait until the Undead have been dispatched. Then Move north into the harbor, healing everyone, while possibly leaving one or two choice units to the South of his castle, which would be able to move into it within a single turn (e.g. Kashen). Don't touch the ships or piers though! Place your units with Magic/Arcane attacks between the piers, near the beach. Now, wait until it's daytime, then send in all those units. Use other units to keep the Slurbows busy (on Hard) or kill a couple of Crossbowmen (on Medium).

On Medium you should definitely be able to kill Marg-Tonz on the turn of your initial attack. On Hard, it might take another turn, in which case he'll fill his castle with recruits. Make sure you manage kill him on your next turn or it's going to get rather painful.

Uncharted Islands

Objective: Defeat the enemy leader.
Lose if: Kai Krellis or Cylanna die or turns run out.
Turns: 25/24/23/22 (easy/normal/hard/nightmare).
Starting units: Kai Krellis, Cylanna, all loyal units available.

Get some Citizens to capture villages and some more Citizens and level 1's to serve as cannon fodder to help soak up the awesome damage capability of the first wave of monsters. Then, recall your most powerful units. You need firepower. You also could really use the slow ability of Netcasters and Entanglers. Two healers are probably a minimum. Brawlers have no place here.

Slide the first Citizens around the edges capturing villages. This is mostly to distract the enemy and disperse his units, weakening his first assault wave, which arrives at night. Don't worry about gold—you probably can't start the next scenario with more than the minimum.

Keshan can handle the upper bottleneck section himself or with a small escort. He is good against the tentacles and even the cuttlefish, if he stays healed. If you lack Keshan, then an Entangler will suffice.

Keep everyone else along the middle bottom, using terrain to your advantage. Use the bottom board edge to protect your rear until it is safe to advance. As always, keep an eye on time of day. Use your auras as much as possible: leadership and illuminate (Cylanna is a diviner by now, isn't she?) Use "slows" to keep all your units from dying. You will probably lose a couple leveled-up ones anyway.

If you cannot win by a fair fight, you always have the option of leader assassination, sliding your assassination force along the north edge of the board, while the bulk of your force stays in the middle.

When you finish off the enemy leader, he gives you a loyal Cuttle Fish. It is isn't terribly useful, but cool to have anyway. When the Cuttle Fish levels into a Kraken, he is quite a bit nicer to have.

BilHeld

Objective: Defeat the enemy leader.
Lose if: Kai Krellis or Cylanna die or turns run out.
Turns: 24/22/20/20 (easy/normal/hard/nightmare).
Starting units: Kai Krellis, Cylanna, all loyal units available.

This scenario should be rated "R" for massive violence! Both sides can do lots of damage to the other.

In this scenario you've almost reached Cylanna's mentor Tyegea, but - there's an island of Drakes in your way, and they don't like you, or the Mermen priestesses. So like civilized non-Human beings they'll try to kill you and you'll try to kill them back, to get past their island.

This is a good scenario for you to use any piercing units you may have. Hopefully you haven't been totally ignoring the Spearman and Figher lines. Even L1 units supported by leadership can do quite a bit of damage to drakes, so you can level a few here. If you are short on Gold, prefer piercers over Netcasters and Priestesses/Diviners (although a second healer does help.) On harder difficulty, do recruit more than one Diviner, as well as a Netcaster or two to slow down Enforcers or Arbiters (with their rather deadly First Strike).

On Normal difficulty, and if you're not in a hurry, you can play it patiently and not recall/recruit anyone, aside from maybe a few level zero Citizens, for about four turns. The drakes will take a while getting to you, so just take some villages and let your income work. Don't worry too much about holding the villages; instead, when you feel ready, try to knock out the enemy leader as fast as possible for a good early finish bonus. On Hard, you can't afford to wait, as you'll face many more Drakes that way.

Let the first wave of Drakes come to you. You'll have the advantage in the water — even against high-level units. They might kill some of your weaker units, but you will do far more damage to them, and level up some L1 units in the process. If you survive the first wave, you should be fine. You probably will have to do a little fighting on land towards the end. Just be careful about how many units can attack each of yours.

When you get to the enemy castle, note that the Drake Leader can be lured out fairly easily by putting a melee only unit in his range.

Talking to Tyegea

You've finally arrived at the island where Tyegea, the Diviner and Cylanna's mentor, lives with her Priestesses.

There will be no fighting here. Essentially, Tyegea gives you an errand: Go find a flaming sword for her. She at least gives you the gift of some holy water, which will make the unit who takes it have arcane melee damage. Even with that she's pretty stingy - only one flask of holy water, so you'll need to choose carefully.

Naturally, a unit with a good melee attack, which isn't already arcane (or another kind effective against the Undead) is the right choice - so have one of your leveled fighters (not the one with the Storm Trident) take the water. You should prefer, say, a Triton, rather than a Fighter you expect to promote, since without a special weapon, these units will not be very useful after the next scenario.

The Mage

Objective: Find Caladon the Mage.
Lose if: Kai Krellis or Cylanna die or turns run out.
Turns: 16/17/18/19 (easy/normal/hard/nightmare).
Starting units: Kai Krellis, Cylanna, all loyal units available.

In this small, vertical, swampy level you need to locate a Mage who will tell you where to find the flaming sword, which you will later retrieve for Tyegea. Unfortunately, it is infested with Giant Scorpions and Bats, and there are a few other critters too.

Note that you won't need to fight the Mage (although from his demeanor it seems like he might jump you...) - nor will you have anything else to do on the level, so it's just about getting to a single unit to his position: A white temple in the mid-Northern part of the level. This means you'll need two sub-forces: Scout(s) and Defense/diversion.

Pest Control: The Giant Scorpions are very resistant to impact attacks (70%) and have decent HP - but they're also sensitive to arcane damage, extremely susceptible to fire, and have no ranged attack. So the Storm Trident bearer, the holy-water-equipped unit and Priestesses/Diviners work well. It's especially important to have a second healer in addition to Cylanna, since you're going to get poisoned a lot. You only have a tiny fortress to recruit in - 2 recruits/recalls per turn - but if enough of your loyal units have survived, that shouldn't pose too much of a problem

Stay near your fortress initially - perhaps even to the West of it, in the water. You'll want to form a short line from the Western to the Southern edge of the level, as the Scorpions will swarm on you, and occasionally so will the Bats. The Bats have a more complex behavior: They spawn at night, rally to some point outside their cave (on the same turn), then attack, and finally return their cave for the day. Be careful not to expose wounded units, as while they're just L1 bats, they're very mobile.

Scouts: If you have a Dread Bat, you're basically set. Hang around the edge of the water at the mid-level to avoid the Spiders, and once they've passed you by (probably turn 3 or so) you can move up into land. You might still be attacked on 3rd turn by a Spider or a Scorpion, but you'll survive. Thus you might well find the Mage to your North-East on turn 4. A Blood Bat / Undead Bat is more of a gamble and may not be enough - although you could give it a backup unit, making its advance slower.

Alternatively, Keshan can probably make it. He will be hassled by multiple units, and will be much slower (or you'll need to have him take the Eastern edge of the map, so that he can move on land) - but he'll defend himself pretty well, has HP to spare and can theoretically even rest and cure poison in a village a couple of times. Keshan + a bat would be an even more effective combination.

If you have no good scout, your timing will be very tight (on Hard and Nightmare), and your defensive force should become more offensive, with some more recruits, so that you kill enough creepy crawlers to get some units up North which won't be chased.

The Flaming Sword

Objective: Pry the flaming sword from the dead hands of its owner.
Lose if: Kai Krellis, Cylanna or Caladon die or turns run out.
Turns: 30/28/28/28 (easy/normal/hard/nightmare).
Starting units: Kai Krellis, Cylanna, Caladon, all loyal units available plus one non–loyal merman from your recall list.

This is one of those scenarios where there are a lot of villages, so you will want to start with some level 0 units (e.g., Mermen Citizens), but don't expect them to last long. If you have a large stable of Brawlers, you can start treating them suicidally much like Citizens, as this is just before the last scenario. Finally, you'll want to recall a relatively experienced Spearman, Javelineer or Warrior, which does not already have a magical weapon, to eventually carry the flaming sword; although you could recall one later on in the scenario, or just give it to some Netcaster/Entangler.

When you get near the ruined castle closest to your initial keep (the one to your North-East), a local Outlaw will appear and let you recruit Outlaw units (for this scenario only). Furthermore, if you helped Siddry (the Poacher trapped in a cage in Slavers) escape alive, he will show up here with a group of loyal units to help you (on Normal: A Footpad, a Poacher and two Thugs). They won't come along with you after this scenario, despite their loyalty, so don't get too attached to them.

After you advance to the three adjacent villages in the center, you'll want to retreat just as fast, or at least enter a careful defensive formation - as night will be coming, as well as a nasty wave of high-level Undead. If you only see a couple of ghosts emerging out of the fog, don't be fooled: They are closely followed by Spectres, Wraiths, Banebows, Deathblades etc. - who are just a bit slower. You may wish to send a few weak units to the North-West, backed by a stronger unit with an arcane ranged attack, like an Siren. This will tend to draw some undead that way, making it easier to deal with the ones in the middle.

Towards the end - try to maximize your gold. You will need some for the last scenario.

When you defeat the Lich to try to get the sword, but as soon as the Lich drops it, Caladon teleports in and picks it up. Now, you need to defeat Caladon to get the sword. He grants you time to leave, which is actually a turn to remove any very damaged units from the vicinity, as Caladon is pretty dangerous. You can attack him now, or wait a turn for him to get impatient and attack you. When he attacks, or you attack him, he summons Fire Guardians. He does not also recruit, because that would just be mean. (There is no reason he would have much gold, anyway.) Note that you get a full round to attack him after he's summoned, so if you left some powerful units close to him, you can get him quickly instead of bothering with the Fire Guardians. Or dispatch as many as experience allows without losing the opportunity for killing Caladon.

Getting Help

Withe the flaming sword in your possession, you now sail straight back to Tyegea. She agrees to join you for an attack on Jotha with her priestesses and her gold. This means that in the next scenario you'll gain: A loyal diviner; the ability to recruit priestesses; and 55 (Normal) / 100 (Difficult?) gold, which is all carried over together with whatever you're brought yourself from the mainland.

There's no fighting in this scenario.

Revenge

Objective: Defeat all enemy leaders.
Lose if: Kai Krellis dies.
Turns: Unlimited.
Starting units: Kai Krellis, Cylanna, all previous loyal units plus three new loyal mermen (a hunter, a fighter and a brawler).

It's the last scenario. Losses of loyal units are acceptable. Also, you are relieved of the responsibility of protecting Cylanna. And you gain a loyal diviner, the Kai's grandmother, Tyegëa.

Your minimum gold is 300, but this is likely insufficient, so hopefully you have a good carryover from the previous scenarios, so that your total gold coming into this final showdown is at least about 500 or 600. Recruit one batch of Merman Citizens to capture villages. Recruit Brawlers next, who are good for bashing skeleton types, doubly so when the Brawlers are supported by leadership. Pace your main recruitment to end by turn 5 or 6. Diviners and Priestesses are especially useful in this scenario, to kill Bats and arcane-susceptible Undead, as well as to heal your main force. Remember that you now have the ability to recruit Priestesses, which will come in handy if you don't already have a stockpile of them to recall.

You must kill all the enemy leaders. The choice of which enemy leader to kill first is easy. The enemy leader at southeast is protected by terrain that is nasty to Mermen. Therefore, the bulk of your force should head to the island in the middle. Send only a few Citizens to collect villages in the east. The four toughies at the northwest strait will not bother you if you do not go near them, so steer clear. The middle leader may dart out if you present him with an easy kill. Try to take him down then, as he is tougher in the middle of the island, protected by his recruits. After killing the middle leader, the rest should be downhill. However, keep an eye on the location of the Shadows recruited by the southeast leader, so that they do not surprise you at night. To protect the wounded, stay in line formation whenever Shadows threaten.

Give great respect to the Undead at night, backing off and foregoing attacks. By day, wail on them mercilessly.

Use your halos effects (Illumination and Leadership) - they are key to fending off larger number of units or mounting a inescapable defense at night. Hopefully, Keshan is both alive and a Flameheart - its leadership bonus will be useful.

A few final tips:

The pile of skeleton bones in the West has a special object, the Ankh Necklace, that will provide the wearer with 70% resistance to arcane damage. A good bearer is an Entangler like Gwabbo, who can then slow enemy necromancers with relative impunity.

If you didn't win the ring of strength on the Flight scenario, now is your chance. After killing Mel Daveth, he drops the ring, which "increases the damage of all its owner's attacks by one, and adds three hit-points." Inky or Krellis would be a good choice of bearer.

On turn 10, a squad of Dark Adepts (Easy) or Necromancers (Challenging) arrives on the northern beach. For this reason, your attack on the central island should veer towards the northwest. This way, you can cut them down in daylight with Brawlers backed by leadership.

[Inky, 1.12 / Difficult]: The enemy leaders do not begin recruiting until turn 2, and it is possible to rush and kill the central leader early on before he gets the chance to spend most of his gold. Recall your best veterans at the beginning and send everyone as far northeast as they can go. The central leader can be lured out as early as turn 4 by putting a melee only unit like a brawler in his range. For recruits I would recommend a mix of priestesses and initiates; I would not bother with citizens or village grabbing, though this is a matter of personal style.