Strefan, Maurer Progenitor is a mythic Legendary Creature — Vampire Noble card from Secret Lair Drop (SLD), collector number 2501. Current market price: $7.78 (foil $7.12), TCGplayer market prices via Scryfall.
Flying At the beginning of your end step, create a Blood token for each player who lost life this turn. Whenever Strefan attacks, you may sacrifice two Blood tokens. If you do, you may put a Vampire card from your hand onto the battlefield tapped and attacking. It gains indestructible until end of turn.