Dimir Control aims to counter your key spells while chipping in with cheap flyers and building card advantage through Brainstorm and Augur of Bolas. Breath Weapon is your most important sideboard card here — at instant speed it sweeps their entire creature base, hitting Faerie Seer, Spellstutter Sprite, Augur of Bolas, Ninja of the Deep Hours, and Moon-Circuit Hacker in one shot. Guardian of the Guildpact is your best long-game threat since it has protection from monocolored spells, making it immune to all of their removal (Snuff Out, Cast Down, Suffocating Fumes) and unblockable by their monocolored creatures. Deglamer comes in to answer Relic of Progenitus, which they will board in and which threatens to shut down your graveyard-dependent recursion. We cut Prismatic Strands because Breath Weapon handles their attackers more permanently rather than just buying a turn, and trim Outlaw Medic because its small body and incidental lifegain underperform against a deck that answers it cleanly with Snuff Out or Cast Down.