We talked earlier about how 4 cmc runs rampant through this deck. I think you should look to Varolz, the Scar-Striped . He allows creatures that get taken directly to the graveyard to still be useful. This allows you to play more sorceries like Grisly Salvage and Jarad's Orders effectively. I think Putrefy needs to be in this deck. It helps build Vulturous Zombie . Gaze of Granite is a decent board wipe, that if you have Verdant Haven will help you trigger effectively. Treasured Find is also a card that helps with dredging. I think that the cards that are kind of expensive are Marrow Chomper , Shambling Shell I personally like Dreg Mangler better, and Vulturous Zombie . Just my opinions, I'm sure there's a combo I don't see there.

Golgari Germination , Necrogenesis , and Worm Harvest are also fun token engines.

Hell, now that I think about it this deck has a lot of great combos. Lotleth Troll is a good card. Also, both Bow of Nylea and Whip of Erebos work really well to.