AbilitiesWML

Abilities and their effects

There are two types of abilities: ones that apply to units (called abilities) and ones that only apply when using a particular attack (called specials or weapon specials). A unit may have multiple abilities and an attack can have multiple specials.

Each ability or special defines an effect based on one to three units. Most abilities apply to a single unit, and [filter_self] can be used to determine when the ability is active. Weapon specials apply to two units, which can be filtered either as "attacker" and "defender" (with the obvious meaning) or as "self" and "other" – the unit that possesses the special, and that unit's opponent. When filtering on the "other" unit, you use [filter_opponent].

Leadership-style abilities are a more complex case, as they involve three units. Like a weapon special, there is an attacker and defender, but there is also a third unit that could be referred to as the "teacher". The "teacher" is the unit that possesses the ability, so it is referred to as "self" in the ability. A leadership ability works by temporarily granting a weapon special to either the attacker or the defender. The unit that benefits from this is referred to as the "student", while the unit that does not benefit is simply the "other" unit. When filtering on the "other" unit, you use [filter_opponent], while the student can be filtered with [filter_student].

The [abilities] tag

The following tags are used to describe an ability in WML:

[heals]: modifies the hitpoints of a unit at the beginning of the healer's turn
[regenerate]: modifies the hitpoints of a unit at the beginning of the unit's turn
[resistance]: modifies the resistance of a unit to damage
[leadership]: modifies the damage of a unit
[skirmisher]: negates enemy zones of control
[illuminates]: modifies the time of day adjacent to the affected units
[teleport]: allows the unit to teleport
[hides]: renders the unit invisible to enemies
(Version 1.15.0 and later only) All weapon specials except for [plague], [heal_on_hit], and [swarm] can be placed in the [abilities] tag. These "weapon specials as abilities" will give the weapon special to all attacks the unit has.
Any other tag is valid (for example [dummy]), but will result in an ability that does nothing but report it's there. Note: a dummy ability must have an id for the name and description to display.
(Version 1.15.3 and later only) All the engine weapon specials can be placed in the [abilities] tag now.

Available formula variables in Abilities and Weapon Specials

(Version 1.15.? and later only) When using formulas in abilities and weapon specials, the following formula variables are available:

self: (unit) the unit that has the ability
student: (unit) for leadership-like abilities this is the unit that is adjacent to the unit that has the ability; if affect_self=yes, this is also unit who has ability.
attacker: (unit) for attack-related abilities and weapon specials, this is the attacking unit during the attack.
defender: (unit) for attack-related abilities and weapon specials, this is the defending unit during the attack.
other: (unit) the unit whose stats get modified from the ability. For abilities without 'apply_to=opponent' this is always the same as 'student'.

Common keys and tags for every ability

(Version 1.13.? and later only) All keys inside any ability that expects a numeric value will also accept formulas using Wesnoth Formula Language. In order to use a formula in these keys, you must enclose it in parentheses. However, do not precede those parentheses with a dollar sign like $(...), since that will erase the self variable.

name: the (translatable) name of the ability. If omitted, the ability will be a hidden ability.
female_name: the (translatable) name of the ability when possessed by a female unit. Defaults to name if not specified.
name_inactive: the (translatable) name of the ability when inactive. Defaults to name if not specified; if the ability is supposed to be not displayed when inactive, you must explicitly set name_inactive to an empty string (nothing after the equals sign).
female_name_inactive: the (translatable) name of the ability when inactive and possessed by a female unit. Defaults to name_inactive if not specified. You should thus set female_name as well!
description: the (translatable) description of the ability.
description_inactive: the (translatable) description of the ability when inactive. Defaults to description if not specified.
special_note (Version 1.15.14 and later only) Translatable string, which will be displayed in the unit’s help. See also UnitTypeWML#Special_Notes.
affect_self: if equal to 'yes' (default), the ability will affect the unit that has it.
affect_allies: if equal to 'yes', the ability will affect units from the same and allied sides in the specified adjacent hexes. If set to 'no' it will not affect own or allied sides. If not set (default) it will affect units on the same side but not from allied sides.
affect_enemies: if equal to 'yes' (default is 'no'), the ability will affect enemies in the specified adjacent hexes.
cumulative: if set to 'yes', this ability will be cumulative with the base value for this ability. Beware of the bug with cumulative leadership in 1.16 https://github.com/wesnoth/wesnoth/issues/6466 , more info see below, in "Extra keys used by the leadership ability" section. (Version 1.17.5 and later only), bug fixed.
id: this ability will not be cumulative with other abilities using this id. Must be present if cumulative is anything other than 'yes'.
halo_image: (Version 1.17.22 and later only) if used, the halo specified showed on unit affected by ability.
overlay_image: (Version 1.17.22 and later only) if used, the overlay specified showed on unit affected by ability.
halo_image_self: (Version 1.17.22 and later only) if used, the halo specified showed on unit who has ability when active.
overlay_image_self: (Version 1.17.22 and later only) if used, the overlay specified showed on unit who has ability when active.
[filter]: StandardUnitFilter If the unit owning the ability does not match this filter, the ability will be inactive.
[affect_adjacent]: an adjacent unit that does not match this filter will not receive its effects. There can be multiple [affect_adjacent] tags in a single ability; a unit needs to match any one of these to receive the effects. The side requirement of matching units is defined by the affect_allies and affect_enemies keys. If there are no [affect_adjacent] tags, then no adjacent units will receive the effects.
- adjacent: a comma separated list of any combination of these directions: n,ne,se,s,sw,nw. (See notes)
- [filter]: a StandardUnitFilter. (Version 1.13.2 and later only) The variable $other_unit refers to the unit owning the ability.
[filter_self]: if the owner of the ability does not match this filter, it will not receive the effects of the ability. [filter_self] takes a StandardUnitFilter as argument.
[filter_adjacent]: if an adjacent unit does not match this filter, the ability will not be active and no-one will receive its affects. Takes extra keys adjacent, count, is_enemy, just like in a StandardUnitFilter, with the one difference that, in the absence of a specified count, all listed directions must match (so, with two directiones eg adjacent=n,s, the default is count=2). In fact, it's really a shorthand for a [filter_adjacent] nested within [filter]. The variables $this_unit and (Version 1.13.2 and later only) $other_unit both work as you'd expect. Multiple [filter_adjacent] can be provided, all of which must pass for the ability to activate.
[filter_adjacent_location]: like [filter_adjacent], but filters on locations instead of units. This is a shorthand for [filter][filter_location][filter_adjacent_location].
[filter_base_value]: filters on the value before any modifications; uses the keys equals, not_equals, etc. If several keys are used all have to match.
[event]: EventWML. (Version 1.19.4 and later only) An [event] to be included into any scenario where a unit with this ability appears in. Note that such events get included when a unit with this ability first appears in the scenario, not automatically when the scenario begins (meaning that name=prestart events, for example, would usually never trigger). See WML Abilities. Shortcut of [unit_type][event].

Extra keys used by the [heals] ability

value: the amount healed.
poison: can be one of slowed,cured. slowed means poison will not take effect for adjacent units (it's not related to the weapon special "slows").

Extra keys used by the [regenerate] ability

value: the amount healed.
poison: can be one of slowed,cured.

Extra keys and tags used by the [resistance] ability

value: set resistance to this value.
max_value: maximum resistance value. Default: 0%. (Version 1.17.24 and later only) Default: no limit.
min_value: (Version 1.19.0 and later only) minimum resistance value. Default: no limit.
add: adds to resistance. Note the interaction with sub in #Common_calculations.
sub: subtracts from resistance.
multiply: multiplies resistance value.
divide: divides resistance value.
apply_to: a list of damage types; if left out, the ability applies to all types.
active_on: one of 'defense' or 'offense'; if left out, the ability is active on both.

These keys affect the actual resistance (e.g. -20%), not the damage modifier normally used in [resistance] (e.g. 120).

[filter_weapon]: (Version 1.15.0 and later only) If present, the resistance ability only takes effect when the owner of the ability uses a matching weapon.
[filter_second_weapon]: (Version 1.15.0 and later only) If present, the resistance ability only takes effect when the opponent uses a matching weapon.

Extra keys used by the [leadership] ability

value: the percentage bonus to damage.
add: the cumulative percentage bonus to damage. Note the interaction with sub in #Common_calculations.
sub: the cumulative percentage bonus subtracted to damage.
multiply: multiplies resistance value.
divide: divides resistance value.

Note: cumulative leadership with cumulative=yes and value= doesn't work in 1.16 (but fixed in 1.17.12 and later). To work around use add= or sub= key (it doesn't require cumulative) (https://github.com/wesnoth/wesnoth/issues/6466 ). If you want each instance of a [leadership] with the same id to be added you will be able to reuse cumulative=yes in 1.17.12 and later, otherwise, if you want to add the value of another [leadership] only once even with the same id in several copies, use add.

[filter_weapon]: (Version 1.15.0 and later only) If present, the leadership ability only takes effect when the owner of the ability uses a matching weapon.
[filter_second_weapon]: (Version 1.15.0 and later only) If present, the leadership ability only takes effect when the opponent uses a matching weapon.

Extra keys used by the [illuminates] ability

Because this ability changes the terrain instead of units on it, affect_self, affect_allies, affect_enemies and [filter_adjacent] have no effect.

value: the percentage bonus to lawful units. Units with alignment=lawful do +value % damage when under the influence of a unit with this ability. Units with alignment=chaotic do -value % damage. Units with alignment=neutral are unaffected by this ability. Units with alignment=liminal do -(abs(value)) % damage. value can be a negative number; this is useful if you want to give Chaotic units an advantage instead of Lawful ones.
add: the cumulative percentage bonus to damage. Note the interaction with sub in #Common_calculations.
sub: the cumulative percentage bonus subtracted to damage.
multiply: multiplies resistance value.
divide: divides resistance value.
max_value: the maximum percentage bonus given. Cannot be less than 0. Defaults to 0 if not present.
min_value: the minimum percentage bonus given. Cannot be greater than 0. Defaults to 0 if not present.

Extra keys used by the [hides] ability

alert: the displayed text when the unit is discovered. Default "Ambushed!".

Extra tags used by the [teleport] ability

[tunnel] - a tunnel tag (without the remove key) defining the tunneling source and target hexes, and maybe other conditions. (It automatically applies only to the unit with the ability.) You may use $teleport_unit inside the [tunnel][source] and [tunnel][target] tag for filtering purposes.

Extra tags and keys used by weapon specials as abilities

[filter_student]: (Version 1.15.0 and later only) If present, only the unit matching this filter, either the possessor of the ability if affect_self=yes, or an adjacent unit matching [filter_adjacent] will be affected. Replaces [filter_self] of normal weapon specials.
overwrite_specials: (Version 1.15.13 and later only) If present, allows a special abilities weapon with a numerical value to impose its value and ignore values of abilities or specials of the same type. If overwrite_specials=one_side, the specials and abilities used by the opponent of the unit affected by the ability with this key and applied to it will not be affected. If overwrite_specials=both_sides, all non-key-carrying abilities and all specials of the same type affecting the recipient unit will be affected, even if used by the opponent (used in the macro FORCE_CHANCE_TO_HIT).
[overwrite]: (Version 1.17.22 and later only) Part of overwrite_specials. Allows more flexibility in determining which specials should take priority over other specials of the same type.
- priority: A numeric value to use when determining which special should be used if multiple specials of the same type have the overwrite_specials attribute. Default is 0.
- [experimental_filter_specials]: StandardAbilityFilter Further attributes to filter specials by to determine if it should take priority over other specials. Accepts the same attributes as [experimental_filter_ability].
Other keys and tags appropriate to the specific weapon special.

Macros for common abilities

macro reference

ABILITY_AMBUSH
ABILITY_CURES
ABILITY_HEALS
ABILITY_ILLUMINATES
ABILITY_LEADERSHIP_LEVEL_1 to ABILITY_LEADERSHIP_LEVEL_5
(Version 1.13.2 and later only) ABILITY_LEADERSHIP (replaces the above leadership macros, which are now deprecated)
ABILITY_NIGHTSTALK
ABILITY_REGENERATES
ABILITY_SKIRMISHER
ABILITY_STEADFAST
ABILITY_SUBMERGE
ABILITY_TELEPORT

The [specials] tag

The [specials] tag goes inside the [attack] tag. It can contain the following tags:

[attacks]: modifies the number of attacks of a weapon, in using value, add, sub, multiply or divide attributes
[berserk]: pushes the attack for more than one combat round, using value attribute, value is 1 by default
[chance_to_hit]: modifies the chance to hit of a weapon, using same standard numerical attributes as [attacks]
[damage]: modifies the damage of a weapon, using same attributes as [attacks] and [chance_to_hit]
[damage_type] (Version 1.17.23 and later only): changes the damage type of a weapon
[disable]: disables the weapon
[drains]: heals the attacker half of the damage dealt, using same attributes as [attacks] and [chance_to_hit], value is 50% by default
[firststrike]: forces the weapon to always strike first
[heal_on_hit]: heals the attacker when an attack connects, using same attributes as [attacks] and [chance_to_hit], value is 0 by default
[petrifies]: turns the target to stone
[plague]: when used to kill an enemy, a friendly unit takes its place
[poison]: poisons the target
[slow]: slows the target
[swarm]: number of strikes decreases as the unit loses hitpoints

Any other tag is valid, but will result in a special that does nothing but report it is there.

Common keys and tags for every weapon special

(Version 1.13.? and later only) All keys inside any weapon special that expects a numeric value will also accept formulas using Wesnoth Formula Language. In order to use a formula in these keys, you must enclose it in parentheses.

name: the (translatable) name of the special. If omitted, the special will be hidden from the player.
name_inactive: the (translatable) name of the special when inactive. Defaults to name if not specified; if the special is supposed to be not displayed when inactive, you must explicitly set name_inactive to an empty string (nothing after the equals sign).
description: the (translatable) description of the special.
description_inactive: the (translatable) description of the special when inactive. Defaults to description if not specified.
special_note (Version 1.15.14 and later only) Translatable string, which will be displayed in the unit’s help. See also UnitTypeWML#Special_Notes.
id: this ability will not be cumulative with other specials using this id.
active_on: one of defense or offense; if left out, the special is active on both.
apply_to: one of self,opponent,attacker,defender,both (default: self). Determines who the effects of this special are applied to.
[filter_adjacent]: if an adjacent unit does not match this filter, the special will not be active and no-one will receive its effects. Takes extra keys adjacent, count, is_enemy, just like in a StandardUnitFilter. In fact, it's really a shorthand for a [filter_adjacent] nested within [filter_self], with the one difference that, in the absence of a specified count, all listed directions must match (so, with two directiones eg adjacent=n,s, the default is count=2). The variables $this_unit and (Version 1.13.2 and later only) $other_unit both work as you'd expect. Multiple [filter_adjacent] can be provided, all of which must pass for the ability to activate.
[filter_adjacent_location]: like [filter_adjacent], but filters on locations instead of units. This is a shorthand for [filter_self][filter_location][filter_adjacent_location].
[filter_self]: the special will only be active if the owner matches this StandardUnitFilter (SUF).
- [filter_weapon]: a standard weapon filter, including special=.
- $other_unit: (Version 1.13.2 and later only) The special variable $other_unit refers to the opponent.
[filter_opponent]: the special will only be active if the opponent matches this SUF.
- [filter_weapon]: a standard weapon filter, including special=.
- $other_unit: (Version 1.13.2 and later only) The special variable $other_unit refers to the unit that owns the weapon.
[filter_attacker]: the special will only be active if the attacker matches this SUF.
- [filter_weapon]: a standard weapon filter, including special=.
- $other_unit: (Version 1.13.2 and later only) The special variable $other_unit refers to the defender.
[filter_defender] the special will only be active if the defender matches this SUF.
- [filter_weapon]: a standard weapon filter, including special=.
- $other_unit: (Version 1.13.2 and later only) The special variable $other_unit refers to the attacker.
overwrite_specials: if equal to 'one_side', then only this unit's specials are evaluated. If equal to 'both_sides', then both this unit's specials and any of the opponent's weapon specials that affect this unit are evaluated. If a special with this attribute is active, it will take precedence over any other specials of the same type that do not have this attribute. Don't applied to boolean weapon special like [poison] ,[slow], [firststrike] or [petrifies].
[overwrite]: (Version 1.17.22 and later only) Allows more flexibility in determining which specials should take priority over other specials of the same type.
- priority: A numeric value to use when determining which special should be used if multiple specials of the same type have the overwrite_specials attribute. Default is 0.
- [experimental_filter_specials]: StandardAbilityFilter Further attributes to filter specials by to determine if it should take priority over other specials. Accepts the same attributes as [experimental_filter_ability], (Version 1.19.5 and later only) [experimental_filter_specials] deprecated, use [filter_specials] instead.
[event]: EventWML. (Version 1.19.4 and later only) An [event] to be included into any scenario where a unit with this weapon special appears in. Note that such events get included when a unit with this weapon special first appears in the scenario, not automatically when the scenario begins (meaning that name=prestart events, for example, would usually never trigger). See WML Abilities. Shortcut of [unit_type][event].

Common keys and tags for specials with a value

The [damage], [attacks], and [chance_to_hit] specials take values that specify how those specials modify their respective base values. The [drains] special takes a value specifying the percentage of damage drained (default 50) and [heal_on_hit] takes the amount to heal (default 0; negative values will harm the attacker, but not kill).

value: the value to be used.
add: the number to add to the base value. Note the interaction with sub in #Common_calculations.
sub: the number to subtract from the base value.
multiply: this multiplies the base value.
divide: this divides the base value.
cumulative: if set to 'yes', this special will be cumulative with the base value.
backstab: if set to 'yes', this special will only apply to the attacker, and only when there is an enemy on the target's opposite side (i.e. when the standard backstab special applies). (Version 1.13.2 and later only) This is now deprecated. The same functionality can be achieved with a [filter_adjacent] in [filter_opponent]; see the implementation of the default backstab special for details.
[filter_base_value]: filters on the value before any modifications; uses the keys equals, not_equals, less_than, greater_than, less_than_equal_to, greater_than_equal_to.

Common calculations

Several abilities and weapon specials take the keys add, sub, multiply and divide.

(Version 1.19.4 and later only) add and sub work independently.

Prior to 1.19.4:

If add and sub are used in the same ability, the add is ignored
If add and sub are used in separate abilities with the same id, or with the default id that's used when no id is specified, then the order in which the abilities are encountered controls the calculation, which may change depending on units' positions on the map.

Extra keys used by the [damage_type] special

(Version 1.17.23 and later only)

replacement_type: replaces the attack type with the specified type when [damage_type] is active.
alternative_type: add a second type of attack to the existing type, it is always the one of the two which will do the most damage to the opponent which will be used.

Note: In 1.18, alternative_type may be stronger than expected, as the damage calculations sometimes ignore [resistance] abilities. This is a known bug, which occurs deterministically and will be left unfixed in 1.18.x to prevent Out Of Sync errors.

Note: If a [damage_type] special includes a [filter_weapon]type=, that filter is tested against the base type of the weapon, ignoring all [damage_type] specials.

Extra keys used by the [berserk] special

value: the maximum number of combat rounds (default 1).
cumulative: if set to 'yes', this special will be cumulative with other active berserk specials (on the current combatant, not with an opponent's berserk).

Extra keys used by the [plague] special

type: the unit type to be spawned on kill. When not specified, the default is the unit type of the unit doing the plaguing.

Extra keys used by the [swarm] special

swarm_attacks_max: the maximum number of attacks for the swarm. Defaults to the base number of attacks modified by any applicable [attacks] specials. If this is specified, then the base number of attacks is ignored.
swarm_attacks_min: the minimum number of attacks for the swarm. Defaults to zero. This can be set higher than swarm_attacks_max to cause a unit to gain attacks as health decreases.

The ratio of the unit's current to maximum hit points will be used to scale the number of attacks between these two values.

Prior to version 1.11, a [swarm] special will cause [attacks] specials to be ignored. In 1.11 and later, [attacks] specials are applied before [swarm].

Macros for common weapon specials