The Mindskinner is a rare Legendary Enchantment Creature — Nightmare card from Duskmourn: House of Horror (DSK), collector number 66. Current market price: $3.09 (foil $3.40), TCGplayer market prices via Scryfall.
The Mindskinner can't be blocked. If a source you control would deal damage to an opponent, prevent that damage and each opponent mills that many cards.