Izzet Spellementals is a tempo deck that wins by chaining spells to grow Sunderflock and Hearth Elemental while protecting them with Spell Pierce and Spell Snare, so the first priority post-board is stripping their interaction with Duress before committing your threats. Day of Black Sun serves as a sweeper that cleanly answers a developed board of elementals and crabs, giving you a reset button that their counter suite struggles to answer at sorcery speed since you can wait until their mana is tapped. Shoot the Sheriff and the additional Requiting Hex give you more early interaction to keep their board manageable before you can take over with your larger threats. Ouroboroid and the two copies of Ral Zarek, Guest Lecturer come out because their cost and tempo requirements make them vulnerable to being countered or outpaced on a board where you need to be proactive, and Strategic Betrayal and Maelstrom Pulse are trimmed in favor of more targeted, lower-to-the-ground interaction.