Gravecrawler

Gravecrawler can't block.
You may cast Gravecrawler from your graveyard as long as you control a Zombie.

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

Tormod, the Desecrator

Whenever one or more cards leave your graveyard, create a tapped 2/2 black Zombie creature token.
Partner (You can have two commanders if both have partner.)

Thrasios, Triton Hero

{4}: Scry 1, then reveal the top card of your library. If it's a land card, put it onto the battlefield tapped. Otherwise, draw a card.
Partner (You can have two commanders if both have partner.)