Grixis Affinity wins by leveraging cheap artifacts for Thoughtcast card advantage and deploying Myr Enforcer as a large, hard-to-race threat. Smash to Smithereens and Cast into the Fire pull double duty — they disrupt the artifact engine while adding to our damage total, with Cast into the Fire specifically exiling Blood Fountain and other recursive pieces to prevent value loops. Pyroblast counters Thoughtcast, which is their primary source of staying ahead on cards, and can also destroy blue artifact lands if needed. We trim Reckless Impulse and Chain Lightning since we want our spells to be interactive rather than purely redundant burn, and cut End the Festivities and one Experimental Synthesizer since their creatures have too much toughness for the former to matter and the latter is our slowest card-generating piece. The key danger is Krark-Clan Shaman wiping our board of 1-toughness creatures, so prioritize deploying threats in waves rather than all at once.