Oblivion

Oblivion (虚空), also known as Cleave, is a recurring ability in the series, and has been used by both enemies and allies alike. It is often a destructive, non-elemental physical attack that targets one or all members of the enemy team, depending on the game.

Final Fantasy VI
Oblivion, originally called Cleave, is Cyan Garamonde's final Bushido skill which can be learned at level 70 or can be learned after the Dreamscape scenario along with other skills that Cyan did not learn during the main playthrough. It attempts to inflict Instant Death on all enemies. Those killed by the attack will have their final attack stalled.

Final Fantasy X
Oblivion is the Overdrive of Anima, which inflicts massive non-elemental damage to all enemies. Seymour's Anima and the Dark Anima can use this ability on the party when fought against.

Final Fantasy X-2
Oblivion is used by the boss Anima when fought in the Farplane.

Final Fantasy Tactics Advance
Oblivion is an ability used by the Assassin job class, which inflicts the status Addle on an enemy. It costs 24 MP to use, and is learned for 300 AP from the Masamune.

Final Fantasy Tactics A2: Grimoire of the Rift
Oblivion is part of the Ninja's Ninjutsu skillset and the Assassin's Assassination skillset, and inflicts Addle to an enemy. It can be learned from the Masamune for 300 AP (for Ninjas) and 400 AP (for Assassins), and costs 12 MP to use.

Dissidia Final Fantasy
Oblivion is a Brave attack for Sephiroth. He rises or lowers to be even with the opponent, then dashes forward, striking the opponent multiple times and knocking them down if they are close enough. Sephiroth learns the attack at Level 3, it requires 30 CP to equip and 180 AP to master.

Dissidia 012 Final Fantasy
Oblivion returns as one of Sephiroth's Bravery attacks. It now costs 100 AP to master.