Infestation Sage

When this creature dies, create a 1/1 black and green Insect creature token with flying.

Reassembling Skeleton

{1}{B}: Return this card from your graveyard to the battlefield tapped.

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Wardens of the Cycle

Morbid — At the beginning of your end step, if a creature died this turn, choose one —
• You gain 2 life.
• You draw a card and you lose 1 life.

Tragic Banshee

Morbid — When this creature enters, target creature an opponent controls gets -1/-1 until end of turn. If a creature died this turn, that creature gets -13/-13 instead.

Revenge of the Rats

Create a tapped 1/1 black Rat creature token for each creature card in your graveyard.
Flashback {2}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Vampire Gourmand

Whenever this creature attacks, you may sacrifice another creature. If you do, draw a card and this creature can't be blocked this turn.

Forest

Stab

Target creature gets -2/-2 until end of turn.

Needletooth Pack

Morbid — At the beginning of your end step, if a creature died this turn, put two +1/+1 counters on target creature you control.

Arbiter of Woe

As an additional cost to cast this spell, sacrifice a creature.
Flying
When this creature enters, each opponent discards a card and loses 2 life. You draw a card and gain 2 life.

Swamp

Infernal Vessel

When this creature dies, if it wasn't a Demon, return it to the battlefield under its owner's control with two +1/+1 counters on it. It's a Demon in addition to its other types.