gray merchant deck. goal is to land a gray merchant for at least 5, preferably 7 or 8. beat down w agro 1's and 2's. remove blockers w doom blade and dreadbore extremely liberally. land a 6/6 for 4 manas. watch them struggle while your underworld connections build up card advantage.
1-of's
tymaret - legend so only want 1 (this is always the case. this is an agro deck - dead cards are a killer) , wins games out of nowhere, also a reasonable creature as a 2/2 for 2
rakdos's return - should probably be gray merchant. on turn 5 merchant hits them for al teast 5 most games... discard tends to be less relevant w 2X ts and 4X lifebane
dark prophecy - underworld connections #4, is good in different situations, and you seldom want connections #2 in play. good w merchant
Rakdos, lord of riots - desecration demon #5, is also a legend...still, is so BA i am considering more. many times he will let you drop 12 or 18 power on the board out of nowhere w his sweet ability. have 11 agressive beaters, so drawback is rarely a problem. RR is sometimes a problem, but not usually.
Nykthos, shrine to nyx - legend, so only 1. dead land would be the worst. can get real stupid. everything produces lots of black devotion