"Kusasseicho" is Japanese for "Rotting Growth", which fits this deck to a tee. By rotting your graveyard, your creatures grow.
Varolz, the Scar-Striped is out for blood, and apparently +1/+1 counters, too. Point of the deck is to get Varolz and others pumped up, and either swing for a fatal alpha strike or Flesh / Blood him.
Varolz, the Scar-Striped - a major player in the deck. Get him out quickly (easy, due to his 3 CMC), buff him up with guys like Death's Shadow, then swing.
Death's Shadow, Slumbering Dragon - Your buffers. Exile them with Varolz to buff him or another creature to insane levels.
Flesh / Blood - A nice alternative to
Fling
, the Blood half is the one you want. It's essentially
Fling
, though it doesn't require you to sac your creature, so if it's countered, you won't be left defenseless.
Golgari Charm - An added bonus, allows you to regen Varolz if there are no other guys to sac for his own regen.
Corpsejack Menace - Doubles the amount of +1/+1 counters going onto Varolz or another guy. 2 of them would allow 42 (!!) +1/+1 counters for one Death's Shadow.
Whispersilk Cloak - Gotta protect Varolz, the Scar-Striped.
Lotleth Troll - Get's rid of creatures you need to get rid of in your hand while buffing himself up as well.
Blood Artist - Your creatures will be dying. Might as well punish your opponents for it and help yourself as well.
Rancor - As you might have noticed, Varolz, the Scar-Striped and most others don't have trample. This solves that problem.
Sideboard -
Pithing Needle - Shuts down annoying things
Duress - A much cheaper version of Thoughtseize, and I have other ways of taking down creatures.
Dreadbore - For annoying planeswalkers hidden behind an indestructible wall or such.
Tormod's Crypt - Allows me to shut down anything that runs even partially on the graveyard.
For M15 - If I happen to pull
Garruk, Apex Predator
or Urborg, Tomb of Yawgmoth at the pre-release, they're more than likely going in here. Maybe even Nissa, Worldwaker.