I like the way that the decks is going as far as synergy and theme are concerned. Try changing the mana ratio for this deck so that you won't get mana screwed later, add some blue counter magic like scatter to the wind,
cancel or
dispel, and maybe play some spells that get the maximum effect from having large creatures in your hand like
titan's presence. Plus since you're paying black as well as green
catacomb sifter would be worth having so you can scry as you sacrifice your eldrazi tokens. Make sure you sacrifice the tokens one at a time, that way you can get the most out of looking in your deck (basically multiple scry triggers). Also as long as you are going for the mana ramp you should consider cards like
breaker of armies and
eldrazi devastator to put the hurt on your enemy and put all that elrdazi token mana ramp to good use. If you add more fathom feeders to this deck and incorporate cards such as
hunt the weak to make your eldrazi creatures fight then you can have some serious damage going all around. How are these suggestions sounding so far?