I really strongly agree with Belial's points. I'm going to make a few minor additional suggestions:

Rend the Veil(ex): All of Emrakul's natural attacks and (ex) abilities are treated as effecting incorporeal creatures as if they were corporeal.

Also given that the Eldrazi are supposed to be consuming the world in some way I'd suggest adding to Annihilator something like "For every creature banished this way, Emrakul gains 1d6 temporary hit points with an additional 1 hit point for every hit die the banished being had. These temporary hit points last 1 hour and stack with each other but not with other sources of temporary hit points.

Also, since it appears that it is going in the final version to be pretty heavily casting reliant I suggest:

Whenever Emrakul either banishes or destroys a summoned being (whether through its Annihilator ability or through other means such as a natural attack), Emrakul may recover a spell slot or prepared spell of level strictly lower than the level of the effect that summoned the being.