Moseo, Vein's New Dean is a rare Legendary Creature — Bird Skeleton Warlock card from Secrets of Strixhaven Promos (PSOS), collector number 91p. Current market price: $0.69 (foil $2.76), TCGplayer market prices via Scryfall.
Flying When Moseo enters, create a 1/1 black and green Pest creature token with "Whenever this token attacks, you gain 1 life." Infusion — At the beginning of your end step, if you gained life this turn, return up to one target creature card with mana value X or less from your graveyard to the battlefield, where X is the amount of life you gained this turn.