Right that's it! I must be playing a different game!

[Hazzard]

Super Nova - Can kill, but many does deadly status ailments.

At least you agree it can kill, everyone else I spoke to (online) treat it like it's a "demi" type attack - i.e. it just lowers you HP if that makes sense. (bull?)

I thought that it did something like 15/16 of your max hp.

15/16...what do you mean? It killed one of my characters, cause it does like 3500-6000 HP damage, killed off Cloud, the others had status ailments or one of them had Ribbon equipped.

what i mean is that it does a very high percentage damage of your max hp of your characters. so basically, if they're not at max hp when he does the attack, they die.

Sort of true, but not everything depends on your HP and whether it is Max, it also depends on your vitality and armor equipped at the time, deciding how much you can withstand out of the blow - casting regen on characters at the time helps a lot, but keeping around 1000 from your Max health can still keep you alive in the battle, but I think Super Nova gets more deadly the amount of times Sephiroth uses it - well it aint good to let him get a couple of them, that's for sure.