Oops, All Spells! is a turn-1 capable combo deck that wins by milling itself with Balustrade Spy or Undercity Informer, using Narcomoeba enters-the-battlefield triggers and Dread Return to set up Thassa's Oracle. Grafdigger's Cage is your most impactful answer — it prevents Narcomoeba from entering the battlefield from the graveyard and stops Dread Return from returning any creature, effectively dismantling their entire combo line. Force of Will, Consign to Memory, and Pyroblast all answer their Pact of Negation in a counter war, so prioritize keeping interaction up on the turn they try to go off rather than developing your own combo prematurely. Follow up any resolved disruption with Surgical Extraction to remove the remaining copies of Balustrade Spy, Undercity Informer, or Thassa's Oracle and lock them out entirely. Omniscience comes out because it is too slow for this race and giving an Oops player a free Show and Tell trigger to drop Balustrade Spy is dangerous; keep your plan tight around Sneak Attack and direct Show and Tell into Emrakul or Atraxa for an immediate game-ending threat.