This is a deck I have had for awhile and has gone through a few iterations. It's blast to play, but its a tough deck to play. It relies on Megrim being out quickly, ideally coupled with an Underworld Dream and a Howling Mine: hit opponents with damage for discarding and for drawing cards. Sorceries, instants and creatures, what few I have, are geared mainly towards keeping opponents discarding. The Royal Assassins and Avatars are there to thin the herd you'll inevitably face.
I don't currently have a sideboard for this deck, but i have used some of the cards from the Life Drain black/white deck (mainly the dual colored cards I could cast with black). There are some obvious weaknesses to the deck (single color, few creatures), but that's part of the challenge and the fun. It doesn't win a lot, but when it does it is spectacular!
But, I'll take any input or advice you're willing to give.