Repentant Vampire

Flying Whenever a creature dealt damage by this creature this turn dies, put a +1/+1 counter on this creature. Threshold — As long as there are seven or more cards in your graveyard, this creature is white and has "{T}: Destroy target black creature."

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6o72wc48qppb1he5e24ber.