Omni-Tell wants to Show and Tell an Omniscience or Emrakul, the Aeons Torn into play as fast as possible, protected by Force of Will, Flusterstorm, and Veil of Summer, so Thorn of Amethyst taxes their crucial noncreature spells like Show and Tell, Ponder, Stock Up, and Cunning Wish, meaningfully slowing their combo turn. Null Rod has no relevant targets in their list, so leave it in the sideboard; prioritize Thorn of Amethyst copies and add Disruptor Flute to further tax their key spells. Sire of Seven Deaths and the extra Eldrazi Confluence come out since neither disrupts the combo quickly enough. Chalice of the Void set at one is devastating, stopping Ponder, Brainstorm, and cheap interaction outright, while set at zero it only stops Lotus Petal.