Pontiff of Blight

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.)
Other creatures you control have extort. (If a creature has multiple instances of extort, each triggers separately.)

Maw of the Obzedat

Sacrifice a creature: Creatures you control get +1/+1 until end of turn.

Swamp

Thrull Retainer

Enchant creature
Enchanted creature gets +1/+1.
Sacrifice Thrull Retainer: Regenerate enchanted creature.

Thrull Champion

Thrull creatures get +1/+1.
{T}: Gain control of target Thrull for as long as you control Thrull Champion.

Plains

Kingpin's Pet

Flying
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.)

Blood Pet

Necrite

Whenever Necrite attacks and isn't blocked, you may sacrifice it. If you do, destroy target creature defending player controls. It can't be regenerated.

Soul Exchange

As an additional cost to cast this spell, exile a creature you control.
Return target creature card from your graveyard to the battlefield. Put a +2/+2 counter on that creature if the exiled creature was a Thrull.

Mindstab Thrull

Whenever Mindstab Thrull attacks and isn't blocked, you may sacrifice it. If you do, defending player discards three cards.

Treasury Thrull

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 Treasury Thrull attacks, you may return target artifact, creature, or enchantment card from your graveyard to your hand.

Basal Thrull

Thrull Surgeon

{1}{B}, Sacrifice Thrull Surgeon: Look at target player's hand and choose a card from it. That player discards that card. Activate only as a sorcery.

Breeding Pit

At the beginning of your upkeep, sacrifice Breeding Pit unless you pay {B}{B}.
At the beginning of your end step, create a 0/1 black Thrull creature token.