I've been playing with variations of this:
It can work really well when it works. I'm not sure about consistency. Yogg has won me some games straight out several times, but I'm not convinced he should be the theme of any deck. I really want to play a yogg/cthun hybrid kind of deck but it has way too many cards I want to fit in to it.
Funniest game was when I had cast something like 21 spells in the game and played yogg as my last card, almost ended up fatiguing myself to death but wiped out his last 14 health no problem.