Slaughter Singer is a uncommon Creature — Phyrexian Cleric card from Phyrexia: All Will Be One (ONE), collector number 281. Current market price: $0.29 (foil $0.41), TCGplayer market prices via Scryfall.
Toxic 2 (Players dealt combat damage by this creature also get two poison counters.) Whenever another creature you control with toxic attacks, it gets +1/+1 until end of turn.