This deck attempts to win by chaining together many spells in one turn without even fighting, thanks to 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.

The big weakness of this deck at the moment is a slow start with no one drops. One drops are needed to either slow down the opponent, accelerate the start, or add to the strategy at the 1-drop level. Here are some possibilities:

Slow the opponent:

Forked Bolt
Fog
Nettle Sentinal (they may feel compelled to deal with Nettle Sentinal - but interestingly it also combos well with Holdout Settlement as it may get tapped multiple times in one turn).
Kird Ape - annoying turn 2 threat that opponent must do something about.

Accelerate:

Elvish Mystic
Elvish Pioneer
Utopia Sprawl
Wild Growth

Work with the strategy

* Manaforge Cinder - this one is really really good as any spawn can now be produce a red (or black - which maybe opens up black Eldrazi spawn producers?)
* Orcish Lumberjack - is great if you think you can pull off victory the turn you sacrifice a forest to get the extra 2 mana. If you ran this, you'd probably want to run some extra forests. Would be even more amazing if there was a way to untap this card.
Quirion Ranger - allows you to use forest twice in one turn, and combined with Orcish Lumberjack could help produce a lot of red/green mana.
Orochi Leafcaller
Viridian Acolyte
Wild Cantor
Essence Warden (gains 1 life with each creature entering battlefield)
Glitterfang (bounces back to hand each turn)
Granger Guildmage
Karplusan Wolverine
Goblin Arsonist
Mogg Fanatic
Blister Pod
Arbor Elf
Skyshroud Ranger
Young Wolf
Centaur's Herald
Llanowar Augur (make some use out of one of the non-spawn Eldrazi creatures on the board).
Nettle Sentinel

Other things to consider that are not 1 drops:

Call the Scions
Basking Rootwalla