Fear of the Unknown

Trample When you cast this spell, choose a playtest card you own from outside the game. Exile it. You may cast that card as long as it remains exiled. Mana of any type can be spent to cast that spell. (In a sealed event, outside the game is your sideboard.)

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6o60453csppb1hq83612iq.