Tarrian's Soulcleaver is a rare Legendary Artifact — Equipment card from The Lost Caverns of Ixalan (LCI), collector number 389. Current market price: $3.18 (foil $4.08), TCGplayer market prices via Scryfall.
Equipped creature has vigilance. Whenever another artifact or creature is put into a graveyard from the battlefield, put a +1/+1 counter on equipped creature. Equip {2}