Endrek Sahr, Master Breeder

Whenever you cast a creature spell, create X 1/1 black Thrull creature tokens, where X is that spell's mana value.
When you control seven or more Thrulls, sacrifice Endrek Sahr, Master Breeder.

Bloodflow Connoisseur

Sacrifice a creature: Put a +1/+1 counter on Bloodflow Connoisseur.

Viscera Seer

Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Soulreaper of Mogis

{2}{B}, Sacrifice a creature: Draw a card.

Blasting Station

{T}, Sacrifice a creature: Blasting Station deals 1 damage to any target.
Whenever a creature enters, you may untap Blasting Station.

Vampire Aristocrat

Sacrifice a creature: Vampire Aristocrat gets +2/+2 until end of turn.

Witch's Cauldron

{1}{B}, {T}, Sacrifice a creature: You gain 1 life and draw a card.

Nantuko Husk

Sacrifice a creature: Nantuko Husk gets +2/+2 until end of turn.

Carrion Feeder

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

Vampiric Rites

{1}{B}, Sacrifice a creature: You gain 1 life and draw a card.

Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.

Liliana, Dreadhorde General

Whenever a creature you control dies, draw a card.
+1: Create a 2/2 black Zombie creature token.
−4: Each player sacrifices two creatures.
−9: Each opponent chooses a permanent they control of each permanent type and sacrifices the rest.

Phyrexian Plaguelord

{T}, Sacrifice Phyrexian Plaguelord: Target creature gets -4/-4 until end of turn.
Sacrifice a creature: Target creature gets -1/-1 until end of turn.