Reverse (リバース, Ribāsu?), also known as Undo, is a recurring ability in the Final Fantasy series. In most appearances, it inflicts the status effect of the same name onto the target, causing attacking and healing to have the opposite effect.
Reverse is an Arcane Magick spell that causes healing and damage to have the opposite effect. It has 70% base success rate, which is also affected by the user's Magick Power and the target's Vitality. The License for Reverse is Arcane Magick 6 and costs 70 LP to purchase and 50 MP to cast initially (with the Channeling License the MP will be 45, 40, or 35 depending on the number of licenses). Reverse can be bought in the Muthru Bazaar and the Phon Coast for 7600 gil. Reverse has shortest effect duration of all status effects.
In the Zodiac versions, Reverse is listed as a Green Magick 2 License, costs 50 LP and 20 MP, and is bought at the Clan Provisioner for 7,000 gil. Reverse can be learned by the four mage job classes—White Mage, Black Mage, Time Battlemage, and Red Battlemage.
Undo is a Time Magick spell. The spell has one of two effects; If the target was healed on previous turn, Undo will deal damage to selected unit. If the target was damaged on previous turn instead, the target selected will be healed.
This happens to the target's MP as well as HP. It can be learned from the Crown Scepter for 300 AP and costs 14 MP to cast, and has a range of 3 tiles.