After experimenting with Monoblack Aggro (less Specters and UC, more Herald of Torment, Rakdos Cackler & Tormented Hero) I went back to the traditional build because I miss the card advantage provided by UC. Just won 1st over 6 rounds with this:
I decided to maindeck Doom Blade because I've been seeing so much R/G lately, and wanted to have a stronger G1. The tradeoff with this is that my G1 against the mirror is much, much worse since I have 3 "dead" cards (they still hit Mutavault) - especially with the more traditional MBC builds (4 BB-4 Downfall-2 Devour FLesh).
Oh, and those scrylands should've been U/B or B/W. I wanted to play an MBC with Red for Rakdos' Return and Slaughter Games, but I had Overgrown Tombs instead of Blood Crypts in my bag and didn't realize I didn't switch my scrylands until I drew my opening hand.
I beat Green Devotion (thank god for Doom Blade main!) quickly, before losing to R/G in Round 2 (I boarded wrong for this - I thought he was R/G Monsters, turns out he was R/G Devotion so I left the Drown in Sorrow out - would've helped me a lot).
R3 I go up against Esper Humans/Midrange (the Mihara build) - they were saying that this was a bad matchup for the deck, but I don't get it. Both games I was comfortable with my board position the whole time - maybe I need to play against someone who can pilot it better? Don't know, but so far I still don't know if this matchup is really in our favor or in theirs.
R4 I'm in a mirror match (well, so much for Doom Blade) and promptly lose G1. I steamroll him with Erebos G2, and manage pull ahead in the Pack Rat race (despite him playing first) G3 to win.
R5 I go up against Esper, and ALMOST managed to nick G1 had he not drawn an Aetherling. G2 I won on the back of timely hand disruption, and I pull back to win G3 after BOTH my Erebos were taken care of (D-Sphere and Revoke Existence). Mutavault won me this game, you amazing card, you.
R/G Devotion again for R6, and this time I manage to board correctly. I win in 3 very close matches, with Drown proving pivotal in the final game.
how about 2 Mogis, god of slaughter in SB perhaps? if you have those RB skrylands