This deck attempts to win by chaining together several Eldrazi spells in one turn with no combat, generating damage from Impact Tremors and/or Hissing Iguanar. Two of these 8 cards on the battlefield causes 2 damage from each entry/exit of an Eldrazi spawn token.

I used to think this needed more one-drops to become consistently competitive. With this build, consistency is obtained by having 7 land fetches (terramorphicexpanse, evolving wilds) effectively reducing deck size of 53. Turn one is used to fetch a mountain (or with a lot of luck, play Orcish Lumberjack).

Mana base could be more creative, better.

Gruul Signet?
Gruul Turf?
prismatic lens?

Tinder Wall might be especially good as it's an extra trigger for impact tremors and hissing iguana while also providing the means to continue chaining together many spells.

Cinder wall is also of interest for the same trigger reasons though not as good since it doesn't make mana - though being able to defend well could come in handy.

Wall of Roots is also quite interesting.

Night soil: This is good if you run out of cards and need something to spend mana on that gets creatures onto the battlefield . . .

Another thing to consider is all the creatures I never tap. What can I get for convoke?

Kavu Primarch is interesting
Scatter the Seeds
Sundering Vitae (sideboard)
Sprout swarm (good if there's a standoff board state)