Izzet Spellementals wants to chain cheap cantrips and removal to protect and grow Hearth Elemental and Eddymurk Crab, so Duress proactively strips their interaction like Prismari Charm or Traumatic Critique before they can use it. Strategic Betrayal makes them exile a creature of their choice, so it is best when they have only one creature on the board and they can't sacrifice a lesser one. It also exiles their graveyard, which removes the instants and sorceries that make Hearth Elemental and Eddymurk Crab cheaper and fuel their other graveyard-based value. Erode is cut since giving this deck a free land accelerates them toward their expensive top-end threats, which is the opposite of what we want. Essence Channeler's small body does little against a deck that isn't attacking on the ground early, so it's trimmed in favor of more proactive disruption.