Flying

When Abhorrent Overlord enters the battlefield, create a number of 1/1 black Harpy creature tokens with flying equal to your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

At the beginning of your upkeep, sacrifice a creature.

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

When Acidic Slime enters the battlefield, destroy target artifact, enchantment, or land.

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

Draw two cards.

Whenever Ayara, First of Locthwain or another black creature enters the battlefield under your control, each opponent loses 1 life and you gain 1 life.

{T}, Sacrifice another black creature: Draw a card.

When Eternal Witness enters the battlefield, you may return target card from your graveyard to your hand.

Flying

Whenever Falkenrath Noble or another creature dies, target player loses 1 life and you gain 1 life.

Jarad, Golgari Lich Lord gets +1/+1 for each creature card in your graveyard.

{1}{B}{G}, Sacrifice another creature: Each opponent loses life equal to the sacrificed creature's power.

Sacrifice a Swamp and a Forest: Return Jarad from your graveyard to your hand.

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.)

Devour 2 (As this enters the battlefield, you may sacrifice any number of creatures. This creature enters the battlefield with twice that many +1/+1 counters on it.)

At the beginning of your upkeep, create a 1/1 green Saproling creature token for each +1/+1 counter on Mycoloth.

{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.

When Ravenous Chupacabra enters the battlefield, destroy target creature an opponent controls.

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)

When Shriekmaw enters the battlefield, destroy target nonartifact, nonblack creature.

Evoke {1}{B} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters the battlefield.)