Iainuki

Iainuki, also known as Iai Blow, Iai Strike, Slash, Fdraw, Flash, Sudden Cruelty, or Iai, is a recurring command ability in the Final Fantasy series, and has also appeared as an enemy attack. It typically attempts to instantly dispatch the target. The job class Samurai is most often associated with the technique.

Final Fantasy V
Iainuki is the Level 5 ability of the Samurai, learned for 540 ABP. It usually has a 85% chance to instantly kill all enemies, but takes into account the level factor all magic attacks use and will never work on Heavy targets.

Final Fantasy VII
Iainuki is the Japanese name for the Flash command, the final ability of the Slash-All Command Materia found in the Ancient Forest. It allows the user to attack all enemies and attempt to inflict instant death. The chance for Flash to hit an enemy is equal to the equipped weapon's Atk% halved. Flash has the opposite effect to undead enemies, causing full recovery instead.

Final Fantasy VIII
Iai Blow is an enemy ability used by Forbidden when it has less than 85% of its HP remaining. It does physical damage and has a chance to instantly kill the target.

Final Fantasy IX
Iai Strike is a Sword Arts technique for Steiner. It attempts to instantly kill an enemy. It has 30% accuracy due to a glitch. It is learned by equipping a Rune Sword.

Final Fantasy XI
Iainuki is a special Weapon Skill used only by the Bastokan NPC, Kurt, during the Shadow Reign era. It inflicts damage in a frontal cone and causes a knockback effect on all enemies hit. Its Skillchain property is Detonation, a level 1 Wind skillchain.

Final Fantasy Tactics A2: Grimoire of the Rift
Iai Blow is part of the Flair skillset used by the Parivir class. It attacks a target for damage equal to half a normal attack and has a chance to kill them instantly. It is learned from the Osafune and requires 300 AP to master.

Final Fantasy Dimensions
Iai is a Fusion Ability, unique to the Warriors of Darkness. It combines the Dark Knight's Final Thrust attack with the Summoner's Odin. The warrior singles out a target, and delivers a swift attack that buffets the foe with shockwaves. It deals damage and has a chance to instantly kill by slicing the foe into pieces.

The Ninja Jinnai is seen using Flash several times in the game, which has a similar effect of slicing the target apart. However, the player cannot command Jinnai to use this attack in battle, and it is not an ability the player can gain by using the Ninja class.

Dissidia Final Fantasy
Iai Strike is the Japanese name of one of Sephiroth's Bravery attacks. It is called Sudden Cruelty in the English release. Sephiroth strikes the opponent twice and launches them backwards, initiating a Chase Sequence. The attack costs 30 CP to equip and 180 AP to master.

Iai Strike is an ability connected to the Smiting Soul accessory. This Iai Strike gives the user a 2% chance to inflict an instant Break on the opponent whenever they damage the opponent's Bravery.

Iainuki is the ability of the Samurai card in the Duel Colosseum. When used, the Samurai card discards all Chaos and Boss cards in the hand.

Dissidia 012 Final Fantasy
Sephiroth's Sudden Cruelty and the Smiting Soul accessory return, though their exact properties have been rebalanced. Iai Strike is the name of the effect tied to the Zantetsuken wielded by Gilgamesh, which has a random chance to instantly inflict Break when Gilgamesh randomly uses the Zantetsuken to attack.

Certain accessories also have a related Assist Iai Strike, which has a chance to inflict Assist Break, and EX Iai Strike, which may cause EX Break on an opponent in EX Mode.

Final Fantasy All the Bravest
Iainuki is the ability that is used by the Samurai during battle.