They Came from the Pipes — Duskmourn: House of Horror Commander #14

When this enchantment enters, manifest dread twice. (To manifest dread, look at the top two cards of your library. Put one onto the battlefield face down as a 2/2 creature and the other into your graveyard. Turn it face up any time for its mana cost if it's a creature card.)

Whenever a face-down creature you control enters, draw a card.