needs more Eldrazi and Colossi; Teeka's Dragon is good, too

Piranha Marsh .

still needs more Eldrazi & Colossi ;)

It seriously doesn't :D The Eldrazi are greatly hated in my area, they are not played. And for the colossi there really isn't a use. I don't see the sense of big creatures which don't do anything else... I thought about Piranha Marsh, at first it was in there - but then I sadly realized that CIP tapped is a huge disadvantage. :/

I like it as long as it works in your play group that's all that matters. +1. I'm working on a rakdos deck myself with Exava, Rakdos Blood Witch as my general, you should check it out.

here's a few suggestions, Blood Crypt , Rakdos Guildgate , Rakdos's Return , Mizzium Mortars , Ashenmoor Liege and Geralf's Messenger

you already have Exquisite Blood . why not add Sanguine Bond to finish the combo.

I had a deck similar to this a while back. Super fun. I'd recommend throwing in a Staff of Nin somewhere. Helps ensure you can cast Rakdos and gives you some extra draws to get even more big stuff.

I really like Blightning in any of my Rakdos color decks.

Oh and also, have you considered Bloodgift Demon ?

Actually, I have not... thanks :D

Dread instead of Dragon mage and No Mercy instead of null profusion ,imho

Both of them would be nice, but the rare draw I get with Red / Black is worth much more than killing a few more creatures. Thanks for the input thou...

Goblin Fireslinger , Tormented Soul , and Lobber Crew .

Find room for Quicksilver Amulet and Deathrender efficient way to cheat creatures in to play at all times.

Akroma, Angel of Fury for those rage inducing moments to deal with the azorius players.

Phyrexian Purge

Rakdos Carnarium instead of the Rakdos Keyrune ? I mean all the keyrune asks for is to die and not be mana anymore...

Browbeat? It puts your opponents in a very difficult situation: have your creatures cost 5 less or draw 3 cards.