Nahiri, Forged in Fury

The attack trigger fires on declaration, before blockers, so every equipped attacker banks its exiled card the instant it turns sideways, no combat math required; the clause letting you cast Equipment for free off that exiled card closes the loop, because each new sword you flip refunds itself and can be attached the same turn to feed future attacks. That recursion is the whole design idea: Affinity for Equipment discounts the body onto the board, the body then digs your library for more Equipment (and anything else), and every piece found either feeds back into the attacking engine or, if it's Equipment, hits play at no cost. It rewards a deck that treats gear as its threat base rather than an accessory, and it does so with a keyword built specifically to reward that posture: the more Equipment you already control, the cheaper this arrives to start converting attacks into cards. The 5/4 body accelerates the loop from the front, strapping on its own Equipment to fire the same trigger it feeds. Boros artifact-aggression had circled this shape for years without a piece that both discounted its own curve and paid you for swinging, and the card arrives asking a precise deckbuilding question: how many pieces of Equipment can you fit before the discount and the trigger stop compounding, and how fast can you attach the first one to start turning cards into cards.