Plagued Rusalka

{B}, Sacrifice a creature: Target creature gets -1/-1 until end of turn.

Blind Creeper

Whenever a player casts a spell, this creature gets -1/-1 until end of turn.

Sacrifice a creature: This creature gets +2/+2 until end of turn.

Destroy target nonblack creature. It can't be regenerated.

Flying
Sacrifice a creature: This creature gets +2/+1 until end of turn.

Pay 1 life: This creature gets +2/-1 until end of turn.

{4}{B}, Sacrifice a creature: Return target creature card from your graveyard to your hand.
{4}{G}: Put a +1/+1 counter on target creature.