Lifebreak

Lifebreak, also known as Revenge and ????, is an ability that does damage equal to maximum HP minus current HP.

Final Fantasy V
???? is a blue magic spell.

Final Fantasy VI
Strago Magus uses the Revenge Lore.

Final Fantasy VII
???? is an enemy skill.

Final Fantasy IX
It appears as the Blue Magic spell Pumpkin Head.

Steiner can use Minus Strike.

Final Fantasy Tactics
Similar moves:
 * Archaic Demons can cast Lifebreak.
 * Beowulf's Shock
 * Behemoth's Gigaflare
 * Cloud's Blade Beam
 * Samurai's Meatbone Slash

Final Fantasy Tactics Advance
Templars can use Lifebreak. Snipers can use Doom Archer. However, Doom Archer's damage is split between HP and MP.