Delay Buster is a skill affecting the specific number of turns within the Act List. It appears within Tidus's section of the Sphere Grid. It moves the next opponent's next turns down the Act List greatly and costs 18 MP to use.
Valefor's special attack, Sonic Wings, also causes Delay. If the player has Valefor's Agility stat high enough, and is facing a particularly slow enemy, the player can cast it repeatedly without the opponent ever getting a turn.