No sideboard, because who am I kidding? The point is to get a Vampire Hounds in play, a Shambling Shell in your hand, and 3 or so Eidolons either in the yard or your hand; discard eidolons, cast shell, sac shell, dredge, continue attacking each turn with a 12/12 or more hound until opponent is dead. Obviously super fragile to unconditional removal; I got blown out by someone playing Kessig Recluse/Prey Upon.dek.
I kind of want to play this with blue, so that I can abuse Tolarian Winds and Cavern Harpy, but then I won't even have the Wild Mongrels as a backup plan (and the Putrid Leech as a backup to the backup).
The problem is that you can't remove the dredgers for the eidolons as both the imp and the lizard have extremely relevant bodies and abilities.
The imp is a flying creature with Deathtouch that comes back every turn when you need it.
The lizard allows you to turn black mana into life with TE and is a decent blocker thanks to its 3 toughness.
The eidolons are 2/2s for 4 mana. Their abilities aren't great as well. When you have an imp or a lizard in your hand without an engine card in play, you have at least a decent creature. When you have an eidolon, you have basically nothing.
Blue-black does seem like a better way to go; I hate to lose the mongrels as an alternate win condition (and the shambling shell is more resilient against countermagic than the harpy as blaat noted), but you get access to a lot of better multicolored spells that way.