Grixis Affinity is black-based with a handful of blue cards, namely Thoughtcast and Utrom Monitor, so Red Elemental Blast and Pyroblast have real targets: they can counter a Thoughtcast or Utrom Monitor on the stack, or destroy a resolved Utrom Monitor. Refurbished Familiar is black, so these cards can't touch it. Smash to Smithereens is tempting given their artifact-heavy board but is omitted here in favor of maximizing our blue-hate, since countering their card draw (Thoughtcast) or removing key blue threats is higher impact. This is primarily a race against a deck that leans on powerful artifact creatures like Myr Enforcer that become cheap through affinity, so keep the core burn engine fully intact and prioritize speed. Guttersnipe and the slowest card-advantage spells come out to make room.