Corpses of the Lost is a rare Enchantment card from The Lost Caverns of Ixalan Promos (PLCI), collector number 98p. Current market price: $0.99 (foil $0.49), TCGplayer market prices via Scryfall.
Skeletons you control get +1/+0 and have haste. When this enchantment enters, create a 2/2 black Skeleton Pirate creature token. At the beginning of your end step, if you descended this turn, you may pay 1 life. If you do, return this enchantment to its owner's hand. (You descended if a permanent card was put into your graveyard from anywhere.)