Ur' better off dead

As a fan of master of cruelties, I must say I like this deck. I've toyed with this idea myself and I would suggest also looking at cheap creatures with deathtouch and giving them the ability to ping with Power of Fire. That way by turn 2 you have a consistent killer for creatures. There are a few one drop black creatures with deathtouch so it's easy enough to do and won't upset your curve at all. The hard part is finding room for them in here.

My biggest issue with the deck is the amount of land in it. I only have one deck that sits in the range of less than 16, and that's because after much testing the deck always had too much land and not enough of anything else to make it work. That being said, I can say just from looking at this that it will mana screw you a lot. My suggestion is to maybe drop a few spells like Brimstone Volley and Infernal Plunge and either add more land, or add some draw spells like Sign in Blood or Tormenting Voice, or both if you so choose. You do need at least 4 more land though, otherwise this deck will flop a lot.

Ok, criticism aside, I have something I like to share with people that play rakdos. Rakdos decks are some of the hardest decks to do properly because everyone plays them the same way. Everyone tries to include ways to keep themselves alive, and in so doing they completely butcher the entire concept of rakdos. Rakdos is literally about sharing the pain. That's why things like Havoc Festival exist. My personal rakdos deck is made up of only RTR and Theros block cards, and it will literally kill me if I don't kill you first. I built it like that on purpose. The reason is because by doing it that way I'm able to go all out and put my opponent in a bad spot because I don't care about taking damage. That allows me to make them take the defensive and then massacre their life points before they get the chance to fight back. Rakdos strikes fast and hard with no concern for its safety, so play like it, and watch your foes perish!