Underhanded Designs is a uncommon Enchantment card from Kaladesh (KLD), collector number 104. Current market price: $0.18 (foil $0.91), TCGplayer market prices via Scryfall.
Whenever an artifact you control enters, you may pay {1}. If you do, each opponent loses 1 life and you gain 1 life. {1}{B}, Sacrifice this enchantment: Destroy target creature. Activate only if you control two or more artifacts.