Sever the Bloodline is a rare Sorcery card from Duel Decks: Blessed vs. Cursed (DDQ), collector number 63. Current market price: $0.10, TCGplayer market prices via Scryfall.
Exile target creature and all other creatures with the same name as that creature. Flashback {5}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)