Esuna

Esuna is a recurring White Magic spell in the Final Fantasy games. Its first appearance is in Final Fantasy II. Esuna can be used to cure most types of negative status effects just like its item equivalent, Remedy.

Final Fantasy II
In Final Fantasy II, a party member can learn Esuna from an Esuna Tome. At level 1, Esuna can only cure Poison and Darkness, but as the spell levels up, it can cure more types of status effects. At level 2, it can also cure Curse; at level 3, it can also curse Amnesia; at level 4, it can also cure Toad; and lastly, at level 5, it can also cure Stone. During a battle, if a party member uses an Esuna Tome, they cast a level 8 Esuna, which has the additional effect of curing KO.

Final Fantasy IV
In Final Fantasy IV, Esuna can be used by both Tellah and Porom through the White Magic command.

As the party enter a hallway following the defeat of Cagnazzo, the walls of the room start closing in on them. Palom and Porom sacrifice themselves by turning into stone statues, which stop the wall from moving, allowing the rest of the group to escape. While Tellah tried to use Esuna to cure the petrified twins, the spell fail to cure them as they petrified themselves and thus cannot be cured.

Final Fantasy Mystic Quest
In Final Fantasy Mystic Quest, the Heal spell is found at Falls Basin. It functions identically to Heal Potions, as it can cure any status effect.