Gonti's Machinations is a uncommon Enchantment card from Aether Revolt (AER), collector number 63. Current market price: $0.28 (foil $4.88), TCGplayer market prices via Scryfall.
Whenever you lose life for the first time each turn, you get {E}. (You get an energy counter. Damage causes loss of life.) Pay {E}{E}, Sacrifice this enchantment: Each opponent loses 3 life. You gain life equal to the life lost this way.