Discover

Cards carrying the Discover keyword. Discover N exiles cards off the top of your library until you reveal a nonland card with mana value N or less, then lets you either cast that card without paying its mana cost or put it into your hand, with the rest going to the bottom. Geological Appraiser triggers Discover on entering the battlefield, while Quintorius Kand uses a loyalty ability to Discover. Unlike Cascade, which only lets you cast the hit for free, Discover gives you the choice to bank the card in hand instead, and it cares about mana value at or below N rather than strictly less than the source's cost.