Woodlurker Mimic

Whenever you cast a spell that's both black and green, this creature has base power and toughness 4/5 until end of turn and gains wither until end of turn. (It deals damage to creatures in the form of -1/-1 counters.)

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6onimth5kdpb1hqyhk32gx.