Regen (ability)

Regen is both a positive status and the spell that causes it. It appears in various games in the series. Characters afflicted by Regen gradually recover HP over time, however, it has the exact opposite effect if the character is undead, where it gradually reduces one's HP, as if poisoned. This also applies to enemies, meaning that casting Regen on an Undead will cause it to lose HP. In other cases, Regen does not work at all against an Undead. Regen is the opposite of Seizure.

Final Fantasy IV
FuSoYa has the Regen command, which was removed from the SNES version. It restores a very small amount of HP over time to the party. (Usually 10 HP)

Final Fantasy V
Regen is a Level 1 Time Magic spell that targets a single character.

Final Fantasy VI
Regen is learned from Kirin and Starlet. Kirin's ability Life Guard casts Regen on the entire party.

Final Fantasy VII
Regen is learned from the Cure Materia. This spell was more powerful than Cure 2, allowing the player to regenerate HP constantly instead of a set interval. A glitch involving lifting up the disc cover lets the player restore all their HP while the enemy does nothing.

Final Fantasy VIII
Regen can be Drawn from various enemies or Draw Points and cast on allies or Junctioned to stats. Regen can be used to slowly damage the Undead.

Final Fantasy IX
Regen appears as a white magic spell, learned by Eiko. There is also the Auto-Regen ability usable by most characters.

Final Fantasy X
Regen is a white magic spell found in Yuna's part of the Sphere Grid.

Final Fantasy XI
There are three versions of Regen; Regen, Regen II, and Regen III. Regen is available to both Red Mages and White Mages starting at level 21, and anyone with one of those jobs as a subjob starting at level 42. The spell regenerates 5HP every 3 seconds (commonly known as a tick), a moderate amount. It will restore 125HP over its duration. Regen II and Regen III are available only to White Mages and are too high level for anyone to get even with a subjob. Regen II regenerates 12HP every 3 seconds, and Regen III will regenerate 18HP ever 3 seconds.

Final Fantasy XII
Regen is available on White Magick 4 License for 35LP. The spell itself costs 1900 gil and uses 16MP each cast. Regen can be used to counter the Sap status effect.

In the International Zodiac Job System version, Regen's License is White Magick 6, available in Mt. Bur-Omisace. Regen can be used by three job classes; White Mage, Red Mage and Knight, although Knights must acquire the Esper Mateus License first.

Final Fantasy XII: Revenant Wings
The Regen status effect is bestowed by the spell Regenga, learnable by Ashe and the Time Mage. Basch can also user Inner Peace to grant himself Regen.

Final Fantasy Tactics
Regen is learned by the White Mage class for 300 JP. Regen can be used to counter the Poison status effect and vice-versa. Regen does not work on the undead.

Final Fantasy Tactics Advance
Auto-Regen is available to Hunters and Snipers as Reaction Abilities. A Defender's Aura skill bestows Regen along with Auto-Life. The Summoner's summon, Kirin, bestows Regen in an area.

Final Fantasy Crystal Chronicles: Ring of Fates
Regan is a bonus effect added to certain armors. It recovers either HP or SP.