Stab

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

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Pulse Tracker

Whenever this creature attacks, each opponent loses 1 life.

Infestation Sage

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

Fake Your Own Death

Until end of turn, target creature gets +2/+0 and gains "When this creature dies, return it to the battlefield tapped under its owner's control and you create a Treasure token." (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Eaten Alive

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

Sanguine Syphoner

Whenever this creature attacks, each opponent loses 1 life and you gain 1 life.