Thorn of Amethyst taxes Doomsday, Dark Ritual, Ponder, and Brainstorm, making their combo turn significantly harder to assemble with correct mana. Null Rod shuts off Lion's Eye Diamond's sacrifice ability, a key combo piece for generating the mana needed to find Thassa's Oracle. Chalice of the Void set at one is outstanding, locking out Dark Ritual, Ponder, Brainstorm, and other one-mana pieces before they can go off. Sire of Seven Deaths and It That Heralds the End are too slow and irrelevant to the actual race against a turn-2-3 kill attempt.