Izzet Prowess relies on small, cheap creatures like Dragon's Rage Channeler, Monastery Swiftspear, and Slickshot Show-Off, which Unholy Heat kills efficiently and which die outright to its delirium-fueled 6 damage. Magebane Lizard is excellent here since their deck casts a huge volume of cheap noncreature spells (Lava Dart, Preordain, Expressive Iteration) each turn, racking up damage fast. Street Wraith's swampwalk does nothing against a deck with no Swamps, and the extra Mishra's Bauble is less important than proactive damage and removal in this fast matchup. Be mindful that Lightning Bolt and Unholy Heat are both vulnerable to Mutagenic Growth combat tricks, so hold removal until combat is resolved when possible.