Boosts damage dealt to foe by 50% of damage dealt to unit.
This family of Specials deals damage based on the unit's missing HP. Retribution is the base skill which can be upgraded into Reprisal and Vengeance. These specials deal increased damage based on the amount of missing HP a unit has, and work from percent. Vengeance deals 50% of a unit's missing health in damage, while Reprisal deals 30%. For example: A unit with 40 max HP and only 10 remaining (30 missing HP), would deal an extra 15 damage with Vengeance and an extra 9 damage with Reprisal.
The way these specials are calculated means that units with a higher maximum health can deal more damage. Generally speaking, Reprisal is the more favored of the two specials thanks to its lower cooldown. Skills such as Desperation or the use of Brave weapons can allow one to attack and KO multiple foes while at low HP. Fury is a great skill which can go a long way towards safely entering low HP. Reciprocal Aid and Ardent Sacrifice can help a unit get to low HP in order to sweep with these specials. Micaiah is one unit who can make use of her unique Sacrifice ability to safely reach 1 HP and use one of these Specials. Vantage and Wrath form a deadly combo that with Reprisal, can guarantee heavy damage so long as the unit is at low HP.
The biggest problem with this family of skills is their poor scaling when compared to other specials. Moonbow charges as quickly as Reprisal, and has arguably better scaling which works from full health. Vengeance’s place is threatened by Luna and Bonfire/Iceberg. Luna and Bonfire/Iceberg both scale off defense/resistance (the targets, or the user’s) dealing reliable damage not dependent on health. Damage dealt through Reprisal and Vengeance is difficult to anticipate compared to damage through skills such as Ignis, who bases its calculations from the unit’s own stats. Finally, sending units on low HP into combat is a risky strategy, particularly in the Arena where deathless runs are desired.