Tempest Trapper

{T}: Add two mana in any combination of colors. Spend this mana only to cast instant or sorcery spells. Whenever you cast your third spell each turn, exile a random card from your library. Until end of turn, you may play that card without paying its mana cost.

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6oc87r8esppb1hmy938da9.