No Secret Is Hidden from Me is a common Scheme card from Duskmourn: House of Horror Commander (DSC), collector number 349. Current market price: $0.58, TCGplayer market prices via Scryfall.
When you set this scheme in motion, exile cards from the top of your library until you exile a nonland card. You may cast that card without paying its mana cost. Then if you control six or more lands, repeat this process once.