Glass-Cast Heart is a rare Artifact card from Crimson Vow Commander (VOC), collector number 18. Current market price: $0.38, TCGplayer market prices via Scryfall.
Whenever one or more Vampires you control attack, create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this token: Draw a card.") {B}, {T}, Pay 1 life: Create a 1/1 white and black Vampire creature token with lifelink. {B}{B}, {T}, Sacrifice this artifact and thirteen Blood tokens: Each opponent loses 13 life and you gain 13 life.