I think there are an awful lot of ways to build this deck.
Vile Aggregate,
Flayer Drone, and
Sky Scourer encourage you to fill the deck with colorless cards, and there are indeed enough colorless cards to make this possible.
Forerunner of Slaughter and
Flayer Drone also provides a touch of colorless synergy but do not really require colorless to work.
While the "colorless matters" cards are all decent, none of them are really amazing IMO, except
Vile Aggregate which can easily be a 5/5 or better for only 3 mana. But he doesn't actually need colorless spells to function - cards that provide thopters also work, Chandra's Parents like to work with this guy. I think taking the deck in this direction would involve removing all or most of the black cards in favor of red cards and artifacts - aggressive red cards, eldrazi mimic, juggernaut etc. Red + colorless is a different archetype entirely. I think black adds some utility but makes the manabase more complicated.
Wasteland Strangler wants sources of exile to work. At only two copies, I do not consider this an important synergy. If we have exile sources it is a good card, if we don't I would rather not warp the deck in order to squeeze this guy in.
Overall this is a hard deck to build because there are a lot of medium quality cards and few truly outstanding cards. I can see different builds being viable.
*Edit* Is mono red + colorless better?
Here is a link to Rabblemaster's
list.
http://forum.nogoblinsallowed.com/viewtopic.php?p=459488#p459488. Although
adds a few nice toys, I think it might not be worth it. The "colorless matters" theme can feel a little forced in Rakdos colorless.
I am not trying to rain on everyone's parade here, but I have been trying to see if a two color + colorless (non ramp) list is viable, and IMO the mana problems just aren't worth it. If you want a
list just for the sake of it that is fine, but I think it helps to look at the
list for a comparison at the very least. I think the lists are roughly equivalent without considering mana, but I hate
Crumbling Vestige and I love the extra strength/wipe resistance of
Ruins of Oran-Rief and
Foundry of the Consuls. Plus
Blighted Gorge is excellent at providing reach to take out those last few HP.
Is there something I am missing? Do I overemphasize how much the 3 "color" manabase hurts BR devoid?