Izzet Affinity leans on Chalice of the Void and a dense artifact-land manabase, so Thoughtseize comes in to strip a Chalice or key payoff before it resolves. Boseiju, Who Endures gives a proactive answer to Urza's Saga, Chalice of the Void, or Seat of the Synod via its channel ability while still functioning as a land, so it isn't a non-land replacement concern. Pulverize sacrifices two Mountains to destroy all artifacts, wiping their Mox Opal, Kappa Cannoneer, and Pinnacle Emissary board for free since we run Taiga and Badlands as Mountain-typed lands. Song of Creation and Gaea's Will are cut as they are slow value pieces that don't advance the actual storm plan against a deck that can lock us out with Chalice, and the extra Tendrils of Agony copy and Runehorn Hellkite are redundant with the kill already achieved via the maindeck Tendrils and Burning Wish package. This keeps the core ritual/storm engine fully intact while adding cheap disruption and a clean artifact sweeper.