All Lucky 7s is a special Easter Egg status in Final Fantasy VII. It occurs when a unit's HP lands on exactly 7,777, causing an in-battle message to say "All Lucky 7s!". When it happens to a player character they will barrage all enemies uncontrollably with each of the 64 hits doing 7,777 damage and the character's name flashing in the battle menu (To a damage total of 497,728HP). Afterward, all subsequent attacks will hit for 7,777 damage until the character's HP changes. After the battle the character's HP falls to 1 so that the effect cannot happen indefinitely.
If an enemy is defeated during the barrage of 64 attacks, the character in the status will stop attacking that enemy, but the death animation will not play until the barrage of attacks is finished. If multiple characters fall into the status simultaneously, they will take it in turns to attack. Each character can only unleash the barrage of attacks once per battle, and while they can leave and re-enter the status, only the effect of inflicting 7,777 damage will occur the subsequent times.
If enemies enter a Lucky 7 state their attacks will do 7,777 damage upon connecting with the player, making it an extremely dangerous state.
If a player is in both the All Lucky 7s status and the Poison status they will take 7,777 damage from the Poison and die. This is because the damage taken from Poison is considered damage the player inflicts to themselves.
As the chance of All Lucky 7s happening spontaneously is low, the player can manipulate the character's HP to get it to 7,777 to trigger the status. The best is if one manipulates a character's Max HP to 7,777, but this is difficult to achieve, as HP growth is randomized. If the player has less than 7,777 HP they can try to get the last two digits of a character's HP to 77 (for example by being hit by mini or frog enemies), and then use Potions and Hi-Potions to get the HP to 7,777.
An easy way to get to 7,777 HP is in the battle against Emerald Weapon; Emerald Weapon's Aire Tam Storm deals 1,111 damage per equipped Materia; a character with 9,999 HP needs to take 2,222 damage to get to 7,777, which is achieved from Aire Tam Storm by equipping two Materia on said character. The Cat's Bell accessory can also be used; while it will always leave the character on an even amount of HP and thus cannot directly achieve an HP value ending in 77, it is possible to use it to reach 154 HP (or any other number that, when halved, results in 77) and cast Demi2 or Laser on the character.