Izzet Prowess is fast and aggressive with Monastery Swiftspear, Soul-Scar Mage, and Emberheart Challenger, so you need cheap interaction more than expensive top-end. Quantum Riddler is a sturdy 4/6 flyer that Burst Lightning can't kill even when kicked, but at five mana it lands too late against a deck that starts pressuring you on turn one, so it comes out. Spell Pierce is excellent here since their deck is full of cheap noncreature spells they need to resolve on curve, like Burst Lightning, Reckless Rage, Sleight of Hand, Flow State, and Stormchaser's Talent. Keep in mind it can't touch their creatures, and it is weakest once they have spare mana to pay for it.