Witchstalker

Hexproof (This creature can't be the target of spells or abilities your opponents control.) Whenever an opponent casts a blue or black spell during your turn, put a +1/+1 counter on this creature.

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6obsq681ujpb1hryatp7rp.