They Came from the Pipes is a rare Enchantment card from Duskmourn: House of Horror Commander (DSC), collector number 14. Current market price: $0.33, TCGplayer market prices via Scryfall.
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.