"BlueDragonX"
Has there been an idea, that deals with something along the line of "mana contamination?" I've been trying to come up with something like that for a while, the only thing I can come up with so far is that the universal energy force, mana, has been "poisoned" and the MC, Souma and his companions have to either a.) find the fragments of the Purifying Flame Crystal or b.) travel to the 8 towers that properly keep the mana in check and keeps them pure, and get them back online. I'm not sure which one of these choices will make a better idea.
Hate to burst your bubble, but A has been done by Final Fantasy countless numbers of times, and B was basically done by Stephen King's "The Dark Tower".
Mana contamination is an interesting though, though. I'd say that you could improve the idea by having characters that "use" mana or "live off" of it, and cannot live without it/without using it, and thus they have to pay the price because it is basically toxic.
Whether or not this leads to a zombie takeover is your choice.
blaugh