Izzet Prowess is a mirror-ish tempo matchup, so Mystical Dispute is excellent both as a cheap counter against their Lightning Bolt/Unholy Heat removal on your threats and, at {1}{U} against a blue deck, as an efficient answer to their own Cori-Steel Cutter or Expressive Iteration. Strix Serenade adds another cheap interactive spell to fight over the board in a matchup that comes down to efficient sequencing and card advantage. Keep Metallic Rebuke and Unholy Heat in since both decks are racing on similarly cheap, artifact-light boards where tempo matters most. This matchup is a race — prioritize proactive plays and use your counters reactively only on their most important spells.