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 kills the target . The job class Samurai is most often associated with the technique . Appearances . " 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 Art for Steiner that attempts to instantly kill an enemy . It normally has 30 % accuracy , but due to the Thunder Slash glitch that persists in North American releases , Iai Strike ' s hit rate is much higher . It is learned by equipping a Rune Blade . " 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 . 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 with a chance to kill them instantly equal to that unit ' s critical hit rate . 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 . " Final Fantasy Legends II " . 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 . " Final Fantasy Brave Exvius " . Iai Strike is a special ability that allows the user to inflict instant KO to all enemies . It has a 30 % chance of succeeding and costs 12 MP to cast . Cyan ( at level 60 , 4★ ) and Gilbert ( at level 75 , 5★ ) are the only units that can learn Iai Strike .