The Relayer Caves

{t}: Add {c}. {3}, {t}, Discard a card: Create a 2/2 white Knight creature token with vigilance. {I}Delirium{/I} — Whenever you attack, if there are four or more card types among cards in your graveyard, you may sacrifice The Relayer Caves. When you do, each player shuffles all creatures they own, their hand, and their graveyard into their library, then draws three cards.