how the hell did none of the 7922 previous heroes ever actually kill him? I mean by his own admission his heart is essentially unprotected (except by his own efforts) when he changes forms and you are telling me no hero ever thought to himself "why don't I aim for that crystallized thing in his chest that looks like a weak point?", especially if that thing glows like most magic soul/heart crystals do when enemies actually bother to have such blatant weak points...and more to the point given how a little girl was able to damage it so easily, how did it never get broken by collateral damage when he gets chopped in half at the end of the fight? ...or do revival items work on even him...then is that why heroes HAVE to keep sealing him over and over since killing only makes him go away til the other demons can chuck a corrupted phoenix down on him?