I never liked the materia Slash-all because of Flash. How ever I find mega-all to be successful where the other has failed. It all depends on where your fighting but I like cloud with 4*cut with Mastercommand and HP absorb linked. This lets cloud drain 999 HP with each swing. If the monsters HP is gone Cloud won't drain any though. But with vincint he is good with mega all. take him to a place with tons of monsters and his death penatly weapon will grow strong. BTW Flash is useless....
Mega-all destruct-added effect.