Izzet Leyline Aggro is a low-to-the-ground red-based tempo deck, so Flashfreeze counters most of their creatures and pump spells (Ancestral Anger, Wild Ride) outright. Tishana's Tidebinder can counter Leyline of Resonance's triggered copy ability (though it won't strip the enchantment's abilities), or counter an ability from a key threat like Stadium Headliner to strip its abilities. Extra cheap interaction matters more than card-disadvantage removal like Bitter Triumph against a fast aggro clock, and We Say Thee Nay! is too slow and mana-intensive against a deck curving out on turns one through three.