Affinity has no red cards, so our burn is never hampered by their sideboard hate like Hydroblast in the way their artifacts are. Red Elemental Blast stays in the sideboard here. Nihil Spellbomb is a small upgrade: it exiles a player's graveyard, so we can use it in response to Blood Fountain's activation to stop them returning creatures from their graveyard. This matchup is primarily a race: our burn kills their small artifact creatures like Refurbished Familiar (2/1) and Baleful Strix (1/1) efficiently, a single Lightning Bolt or Fiery Temper handles Utrom Monitor (3/3), and only the Myr Enforcer (4/4) requires two burn spells. Trim a couple of Highway Robbery, which is too slow against their efficient curve, for the minor upgrade.