Omnislash is performed by Cloud charging up his sword, and then lunging towards an enemy to unleash a barrage of sword strikes, before jumping in the air and charging his final attack that he brings down on the enemy.
OK! Got it!Cloud
As a level 4 Limit, Omnislash is learned from a manual after Cloud has learned all his other Limit Breaks. It is won at the Battle Square in Gold Saucer. If the player wishes to obtain it early on, it can be obtained when the Tiny Bronco becomes available for 51,200 BP. After acquiring the Highwind, it costs 32,000 BP. Once the manual is obtained, the player must use it in the menu for Cloud to learn the ability.
Obtaining Omnislash gains the Omnislash achievement in the PC version re-release. Due to automatically obtaining Omnislash right before for the fight against the final cinematic boss, the player will complete this achievement by beating the game, even if they didn't teach the move to Cloud from the Omnislash manual.
Omnislash performs 15 hits, at 0.75 times Cloud's normal damage each, on random targets. This damage is further increased as each attack is a critical hit, approximately doubling the damage. Omnislash's attacks are all physical and damage depends on Cloud's Strength stat and currently equipped weapon.
Because Omnislash is so powerful, and because Cloud is a mandatory party member, obtaining the Omnislash manual is worth the challenge. It is by far Cloud's most powerful Limit. At its max potential, Omnislash can perform 15 hits of 9999 damage, more than most characters, although doing this will require leveling up Cloud, or greatly improving his Strength stat with Power Sources, even with the Ultima Weapon equipped. Another way to power it up is to use Hero Drinks.
Omnislash is automatically equipped for the final cinematic battle, and is the only command available for the player to use in this battle.