Hand of Vecna is a rare Legendary Artifact — Equipment card from Adventures in the Forgotten Realms Promos (PAFR), collector number 246p. Current market price: $0.78 (foil $0.50), TCGplayer market prices via Scryfall.
At the beginning of combat on your turn, equipped creature or a creature you control named Vecna gets +X/+X until end of turn, where X is the number of cards in your hand. Equip—Pay 1 life for each card in your hand. Equip {2}
All Adventures in the Forgotten Realms Promos cards and prices