Grixis Affinity's board is almost entirely artifacts and artifact lands, making Dust to Dust excellent: exiling two targets at once can remove key threats like Myr Enforcer or Refurbished Familiar, or hit artifact lands. Drossforge Bridge's indestructibility doesn't stop exile effects, so Dust to Dust still answers it unlike destroy-based removal. Relic of Progenitus denies Blood Fountain's creature recursion and can exile all graveyards if needed, though that includes your own. Clowning Around's small tokens trade down badly into their efficient cheap threats, so cut it along with the lone Guardians' Pledge and a Novice Inspector to make room for artifact hate. Dispatch is excellent here too since metalcraft is trivial for you, letting it exile their creatures outright rather than just tapping them.