Thorn of Amethyst taxes Show and Tell and Sneak Attack by a full mana, meaningfully disrupting their ability to cheat in Atraxa, Grand Unifier or Emrakul, the Aeons Torn on curve. The extra Eldrazi Confluence gives us a flexible instant: choosing +3/-3 three times can kill a cheated-in Atraxa, or we can make Eldrazi Scion tokens for extra mana. It replaces the land we trim since we already run a deep Eldrazi-heavy manabase. Chalice of the Void at one is still good, shutting off Brainstorm, Ponder, and Flusterstorm before they can set up. Lotus Petal has mana value 0, so a Chalice at one does not touch it. It That Heralds the End copies come out since their stat boost matters little against a deck trying to cheat in a single giant threat rather than grind with colorless creatures.