This trick requires the Atma Weapon (Cave to Esper World), Offering (In World Of Ruin, Odin's Castle), and approximately 7,000 HP. The Atma Weapon powers up by your HP. With high HP you should be able to do 9,999 damage to every enemy (even Kefka). With the Offering, you will do this four times (39,996 damage) in just one turn.