Thromok the Insatiable EDH

You will want things like doubling season and parallel evolution to get a lot of tokens for devouring purposes. Doubling season you deffinately want because it doubles tokens put out and it doubles counters put on creatures.

Awakening Zone is good to put an eldrazi spawn onto the field every turn for chump blockers, mana ramp or for devouring
Nest Invader puts more spawn tokens in when it comes into play
Things that when they die put more tokens into play for devouring, things like: Brindle Shoat, Mitotic Slime, Penumbra Spider, Thukatongue Thallid

Dragonlair spider is good because it puts more tokens in when other players cast spells

Other devour creatures: Gluttonous Slime, Hellkite Hatchling, Preysiezer Dragon, THunder Thrash Dragon

Helion Eruption is a good card for incase you have a lot of tokens but no devour cards to use them for

Hissing Iguanar will deal damage to opponants whenever another creature dies (ie. when you devour them)
Lumberknot gets bigger when other creatures die
Goblins that deal damage when they die would be good like mudbutton torchrunner and Goblin Arsonist and Magma Pheonix
Other Creatures that do things when they die, like Viridian Emissary that searches up a land

Things that take control of your opponants creatures till end of turn, u can attack with them and then devour them

For other devour creatures go on the Gatherer website at gatherer.wizards.com and search devour
A lot of these cards you can get by buying the Devour planechase deck

Hope this helps, if you get the time pls have a look at my decks: http://www.mtgvault.com/sharpraptor/