Doomsday is a fast combo deck that assembles a pile to win through Thassa's Oracle, typically going off with Dark Ritual acceleration on turns 1-2. Pyroblast is essential here as a hard counter to their blue spells and a way to fight over the Doomsday resolution or Thassa's Oracle trigger. Consign to Memory provides additional interaction that can counter the Oracle trigger even through Cavern of Souls naming Merfolk, making it invaluable in this matchup. Surgical Extraction can disrupt a resolved Doomsday pile by removing a key pile piece. We trim Omniscience as a slower, more expensive threat redundancy in a race where we either need to go off fast or disrupt their combo, and Flusterstorm gets trimmed because Pyroblast and Consign to Memory provide more reliable, unconditional interaction against their critical spells.