Ah good old Yoggy--err Yogg-Saron, whatever I like Yoggy better. Yoggy has influenced the minds of the mortal races of Azeroth for countless years now. Also apparently Yoggy is a girl, I say this because his--her first persona is Sara. So when you're fighting that beast of a million maws, just remember it's a she and don't be insensitive about how big her mouths are.
As for the fight, I have no f@#king idea how to fight this boss, nor am I going to pretend like I do. From what I've read and what I've heard from friends this fight is a lot like C'Thun. Aka this boss is tuff as hell and you're gonna need to do your research on him--err sorry her and be prepared to wipe a lot. Here's a link for a strategy and a description of the boss fight.