This is a mirror match where speed and disruption matter most. Consign to Memory costs {U} and is cheap interaction rather than free: it counters a colorless spell like Lotus Petal, or a triggered ability like Atraxa's enters trigger or Emrakul's cast and annihilator triggers (Emrakul itself can't be countered). Keeping it cheap lets you hold up mana while deploying your own threats. Grafdigger's Cage stays in the sideboard, since neither deck relies on graveyard recursion and Sneak Attack and Show and Tell put creatures onto the battlefield from hand, which Cage doesn't stop. Prismari Charm and Preordain are the easiest cuts since this mirror comes down to who resolves their Show and Tell, Omniscience or Sneak Attack activation first, not incremental card selection. Spell Pierce stays in because their key spells are noncreature.