From The Battle for Wesnoth Wiki
Abilities and their effects
There are two types of abilities: ones that apply to units (called abilities) and weapon-based (called specials). A unit may have multiple abilities, but each attack can only have at most one special.
- heals unit will heal healer_heals_per_turn (see GameConfigWML) hp to all neighbours, up to a total of heal_amount. If a neighbour is poisoned, it will prevent the poison's effect instead of healing.
- cures unit will heal curer_heals_per_turn (see GameConfigWML) hp to all neighbours, up to a total of cure_amount. If a neighbour is poisoned, it will cure the poison instead of healing.
- regenerates the unit will heal itself 8 hp per turn. If it is poisoned, it will remove the poison instead of healing.
- leadership the unit will increase the damage of all neighbouring units by +25% per level difference. (If the neighbouring unit is of a higher level, this effect is negated.)
- illuminates all neighbouring hex will be "illuminated", in other words have a different time of day (See TimeWML). Typically, this will be one step brighter.
- teleport the unit can move between any two allied villages for one move point
- skirmisher the unit ignores zone of control when moving, but still cannot move directly through an enemy unit
- steadfast the unit takes half normal damage when it did not initiate the attack.
- ambush the unit becomes invisible on forest. Invisible units cannot be seen by enemies and do not possess zone of control, although if an enemy moves next to one, it becomes visible again.
- nightstalk the unit becomes invisible during night.
- charge when attacking, both this weapon and defender get double damage.
- poison when this weapon hits, the defender becomes poisoned (see [status], SingleUnitWML).
- slow when this weapon hits, the defender becomes slowed (see [status], SingleUnitWML).
- stones when this weapon hits, the defender turns to stone (see [status], SingleUnitWML).
- magical this weapon always has a 70% chance of hitting.
- marksman when attacking, this weapon has a minimum of 60% chance of hitting.
- drain The controller of this weapon gains health equal to half the damage done (rounded down) whenever this attack hits.
- plague The controller of this weapon is copied onto the tile that any unit this attack killed was on.
- backstab doubles damage whenever there is a unit on the opposite side (location) of the defending unit that distracts it. In 1.0.x the distracting unit must be on the same side (player) as the attacker. In 1.1.x the distracting unit must be an enemy of the defending unit and not incapacitated (e.g. turned to stone).
- firststrike when this weapon is used to defend, the battle proceeds as if it were the attacker (i.e. it attacks first).
- berserk forces the combat to continue until either the attacker or the defender is killed.