Izzet Prowess fields a swarm of small cheap creatures (Dragon's Rage Channeler, Monastery Swiftspear, Slickshot Show-Off) that Pyroclasm's 2 damage sweeps cleanly before they grow with prowess triggers. Spell Snare picks off their two-mana spells like Lightning Bolt-adjacent interaction and Cori-Steel Cutter at instant speed. Thought Scour and Persist are cut since they're too slow and don't block the early aggression well. Keep Fatal Push for their creatures and Thoughtseize to strip removal/burn before it hits our life total, since this matchup is a race we want to control with sweepers rather than individual spot removal.