Border Guardian

Whenever you cast a silver-bordered spell, put a +1/+1 counter on this creature. Whenever you cast a black-bordered spell, this creature can't be blocked this turn. Whenever you cast a white-bordered spell, this creature gains double strike until end of turn.

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6o9wqx6kfppb1h8dn430mt.