Sanguimancy is a uncommon Sorcery card from Born of the Gods (BNG), collector number 81. Current market price: $0.24 (foil $0.38), TCGplayer market prices via Scryfall.
You draw X cards and you lose X life, where X is your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)