Crypt Ghast

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Whenever you tap a Swamp for mana, add an additional {B}.

Gravecrawler

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

Grave Pact

Whenever a creature you control dies, each other player sacrifices a creature of their choice.

Pestilence

At the beginning of the end step, if no creatures are on the battlefield, sacrifice Pestilence.
{B}: Pestilence deals 1 damage to each creature and each player.

Soulstinger

When Soulstinger enters, put two -1/-1 counters on target creature you control.
When Soulstinger dies, you may put a -1/-1 counter on target creature for each -1/-1 counter on Soulstinger.

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

Kalitas, Traitor of Ghet

Lifelink
If a nontoken creature an opponent controls would die, instead exile that card and create a 2/2 black Zombie creature token.
{2}{B}, Sacrifice another Vampire or Zombie: Put two +1/+1 counters on Kalitas, Traitor of Ghet.

Imp's Mischief

Change the target of target spell with a single target. You lose life equal to that spell's mana value.

Mikaeus, the Unhallowed

Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)
Whenever a Human deals damage to you, destroy it.
Other non-Human creatures you control get +1/+1 and have undying. (When a creature with undying dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Carrion Feeder

Carrion Feeder can't block.
Sacrifice a creature: Put a +1/+1 counter on Carrion Feeder.

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Triskelion

Triskelion enters with three +1/+1 counters on it.
Remove a +1/+1 counter from Triskelion: It deals 1 damage to any target.

Ashnod's Altar

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Zulaport Cutthroat

Whenever Zulaport Cutthroat or another creature you control dies, each opponent loses 1 life and you gain 1 life.

Putrid Goblin

Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.