Death Baron

Skeletons you control and other Zombies you control get +1/+1 and have deathtouch. (Any amount of damage they deal to a creature is enough to destroy it.)

Grim Roustabout

Unleash (You may have this creature enter with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.)
{1}{B}: Regenerate this creature.

Clattering Augur

This creature can't block.
When this creature enters, you draw a card and you lose 1 life.
{2}{B}{B}: Return this card from your graveyard to your hand.

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Wall of Bone

Defender (This creature can't attack.)
{B}: Regenerate this creature. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Snow-Covered Swamp

Barrier of Bones

Defender
When this creature enters, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Cabal Coffers

{2}, {T}: Add {B} for each Swamp you control.

Tenacious Dead

When this creature dies, you may pay {1}{B}. If you do, return it to the battlefield tapped under its owner's control.

Nykthos, Shrine to Nyx

{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

Manor Skeleton

Rimebound Dead

{S}: Regenerate this creature. ({S} can be paid with one mana from a snow source.)