Malevolent Awakening

{1}{B}{B}, Sacrifice a creature: Return target creature card from your graveyard to your hand.

Fleshbag Marauder

When Fleshbag Marauder enters the battlefield, each player sacrifices a creature.

Bone Splinters

As an additional cost to cast this spell, sacrifice a creature.
Destroy target creature.

Grave Pact

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

Mortivore

Mortivore's power and toughness are each equal to the number of creature cards in all graveyards.
{B}: Regenerate Mortivore.

Swamp

Blood Artist

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

Geth's Verdict

Target player sacrifices a creature and loses 1 life.

Archfiend of Depravity

Flying
At the beginning of each opponent's end step, that player chooses up to two creatures they control, then sacrifices the rest.

Avatar of Woe

If there are ten or more creature cards total in all graveyards, this spell costs {6} less to cast.
Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
{T}: Destroy target creature. It can't be regenerated.

Gatekeeper of Malakir

Kicker {B} (You may pay an additional {B} as you cast this spell.)
When Gatekeeper of Malakir enters the battlefield, if it was kicked, target player sacrifices a creature.

Reassembling Skeleton

{1}{B}: Return Reassembling Skeleton from your graveyard to the battlefield tapped.