Doomsday needs to resolve cheap cantrips (Brainstorm, Ponder, Consider) and eventually cast Doomsday itself for {B}{B}{B} — Trinisphere taxes their entire cantrip suite and combo pieces up to three mana, making it very difficult for them to find and execute their kill sequence. Simian Spirit Guide is less valuable here since the matchup is decided by disrupting their combo rather than racing, and we'd rather hold Trinisphere's mana disruption plan. Archon of Emeria is outstanding, restricting them to one spell per turn which directly attacks their need to chain multiple cantrips into Doomsday and Thassa's Oracle in a single turn. Magus of the Moon further punishes their many nonbasic fetches and duals.