This is not the aggro deck you normaly go for.
Its about having cretures on the field that get benefits from others. In a way to stay ahead, little control cards are provided so as an artifact (Ghostfire Blade) to beat harder.
There are cards that maybe shouldn't be there, I welcome any suggestion in the comments section.
Tide Drifter Is a solid 0/5 barrier which is the most you can get for 2 mana aganist aggro decks full with small beaters. It also gives +0/1 to other colorless, which is GREAT for delaying profitable attacks and trades.
Herald of Kozilek make your colorless drops 1 mana cheaper and its a 2/4 body.
Ruination Guide is a fair 3/2 with pump to colorless. It ingests.
Kozilek Sentinel is a 2 drop with a 1/4 body that gains attack when you cast colorless. This is a hangarback walker filler.
Eldrazi Skyspawner is a valuable 3 drop. A 2/1 flyer + 1/1 scion makes you hit 2 per turn unless your opponent can block/remove, and even if he so, you stay with a free chump blocker that you can sac to get bigger threats on the field.
Vile Aggregate is also awesome being a */5 body with trample. When * is the number of colorless creatures you control, there is only one in the deck that doesn't count (and it puts 2 colorless on the field!).
Eldrazi Obligator is the most difficult card here to be used at full potential because the only sources of colorless mana are two lands and sac'ing a scion. That condition is not so hard to fulfil, but inconsistency can be present because of this requirement. Doing so, you steal a creature for one turn, which can be fatal in later stages of the game. He also has haste.
Whirler Rogue deliver 3 creatures to the board for 4 mana. Two of those creature are colorless and fly, and it almost make me forgot that the card is a 2/2 drop. He deserves his place in this deck because of the virtual card advantage he provides and also because it fuel Vile Aggregate attack. The thopters can be valuable target for ensoul artifact, turning them into 5/5 flyers.
Drowner of Hope Is a solid 5/5 body that gives 2 scions. The sac effect on him can neutralize bigger threats for defensive/offensive purposes, which gives flexibility.
Endless One can be used to gain/recover tempo, given the fact that we can use him in any turn. It has a special role here, given the fact that the deck doens't have big creatures.
Brutal Expulsion bounces a target and causes 2 damage to another.