Doomsday is a one-card combo deck that wins through Thassa's Oracle or Jace, Wielder of Mysteries after assembling a pile, backed by Force of Will and Veil of Summer to protect the key turn. The race is extremely tight — they can win on turn two or three with Force of Will backup, so you need to either combo faster or disrupt their Doomsday resolution. Unmask is your best discard effect here because it costs zero mana and can strip Doomsday or Force of Will before they're ready to go off; prioritize Unmask over Thoughtseize in your sequencing since they run Veil of Summer post-board which can blank Thoughtseize. Stronghold Gambit is powerful because Doomsday players are holding Force of Will and Doomsday in hand, and the gambit forces them to either reveal their entire combo plan or gamble the flip while you're presenting an immediate Griselbrand threat. Hexing Squelcher reanimated can counter their Doomsday resolution itself, functioning as a counterspell on a creature that bypasses their Veil of Summer protection since it's a triggered ability, not a spell. We trim slower cards that don't contribute to the speed or disruption needed — Cabal Therapy is too conditional without a token to flash it back from, and Archon plus Raph & Mikey are slower targets when the game ends faster.