Grixis Affinity floods the board with zero-cost Myr Enforcers and Refurbished Familiars while drawing cards with Ichor Wellspring and Thoughtcast, and your primary goal is to answer their threats before Galvanic Blast becomes a four-damage Metalcraft finisher. Dust to Dust is an outstanding two-for-one that exiles two artifacts, permanently answering Refurbished Familiar (which recurs from the graveyard) and stranding their engine cards; prioritize taking out artifact lands alongside Myr Enforcer or Refurbished Familiar. Skred and Lightning Bolt handle individual threats, but Dust to Dust and Destroy Evil give you catch-up tools that interact with the artifacts they can't replay once exiled. Thraben Charm (sideboard copy) adds another exile-mode answer for Refurbished Familiar, which is the most dangerous recursive threat. Dispel is weak here as their key plays are sorceries and creatures, and Union of the Third Path is too slow against their fast clock.