Tarrian's Soulcleaver is a rare Legendary Artifact — Equipment card from The Lost Caverns of Ixalan Promos (PLCI), collector number 264p. Current market price: $2.61 (foil $3.39), 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}