Lucky Sevens

[Bubba]

I used it to fight Emerald. It doesn't kill him/her but it does a lot of damage.

You can trick it to happen if you cast mini on an enemy. Just get the last digits 77 and potion your way to 7777.

Detailed trick
1. Have more then 7777 HP.
2. Lower your current HP below 7777
3. Cast mini on enemy so they do 1 damage.
4. Get xx77 HP example : 7677
5. Use potions to make your HP equal 7777

This.

I always start the Emerald Weapon fight packing this bad boy. He's over halfway to death by the time it stops.

Psychotic used the same tactic in his FFVII Steam HD Mod playthrough if you want to see how it works.