Fume Spitter

Sacrifice Fume Spitter: Put a -1/-1 counter on target creature.

Hunger of the Howlpack

Put a +1/+1 counter on target creature.
Morbid — Put three +1/+1 counters on that creature instead if a creature died this turn.

Serrated Scorpion

When Serrated Scorpion dies, it deals 2 damage to each opponent and you gain 2 life.

Wrap in Vigor

Caustic Caterpillar

{1}{G}, Sacrifice Caustic Caterpillar: Destroy target artifact or enchantment.

Carrion Feeder

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

Silumgar Scavenger

Flying
Exploit (When this creature enters, you may sacrifice a creature.)
Whenever another creature you control dies, put a +1/+1 counter on Silumgar Scavenger. It gains haste until end of turn if it exploited that creature.

Life Goes On

You gain 4 life. If a creature died this turn, you gain 8 life instead.

Lampad of Death's Vigil

{1}, Sacrifice a creature: Each opponent loses 1 life and you gain 1 life.

Forest

Caravan Vigil

Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
Morbid — You may put that card onto the battlefield instead of putting it into your hand if a creature died this turn.

Village Rites

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

Nest Invader

When Nest Invader enters, create a 0/1 colorless Eldrazi Spawn creature token. It has "Sacrifice this creature: Add {C}."

Spark Harvest

As an additional cost to cast this spell, sacrifice a creature or pay {3}{B}.
Destroy target creature or planeswalker.

Festerhide Boar

Trample
Morbid — Festerhide Boar enters with two +1/+1 counters on it if a creature died this turn.

Swamp

Tragic Slip

Target creature gets -1/-1 until end of turn.
Morbid — That creature gets -13/-13 until end of turn instead if a creature died this turn.

Somberwald Spider

Reach (This creature can block creatures with flying.)
Morbid — Somberwald Spider enters with two +1/+1 counters on it if a creature died this turn.

Bone Picker

This spell costs {3} less to cast if a creature died this turn.
Flying, deathtouch

Wakedancer

Morbid — When Wakedancer enters, if a creature died this turn, create a 2/2 black Zombie creature token.