Lonis, Cryptozoologist is a rare Legendary Creature — Snake Elf Scout card from Modern Horizons 2 (MH2), collector number 204. Current market price: $0.30 (foil $0.84), TCGplayer market prices via Scryfall.
Whenever another nontoken creature you control enters, investigate. {T}, Sacrifice X Clues: Target opponent reveals the top X cards of their library. You may put a nonland permanent card with mana value X or less from among them onto the battlefield under your control. That player puts the rest on the bottom of their library in a random order.