Affinity is a fast artifact-based deck that wins through Kappa Cannoneer and Pinnacle Emissary backed by Mox Opal acceleration and Urza's Saga constructs — your primary goal is to land a Crashing Footfalls cascade before they can establish a board you can't race. Force of Vigor is your highest-impact sideboard card, destroying key artifacts like Mox Opal, Engineered Explosives, and Urza's Saga for free at instant speed. Brotherhood's End wipes the small-creature and Saga-token side of their board while leaving your rhinos intact. Mystical Dispute replaces Force of Negation as the more mana-efficient counter against their blue interaction (Metallic Rebuke, post-board Consign to Memory, Kappa Cannoneer), costing just one blue mana against those targets. Blood Moon punishes their greedy non-basic land base — they have only a single Island as a basic, so it effectively cuts them off colored spells while your fetch-heavy manabase handles the lock with ease; Subtlety and Fire/Ice come out because bouncing artifacts is too temporary and pinging is too low-impact against a deck that presents 4/4s and ward-protected finishers.