Chandra's Defeat is dead since this opponent has no red creatures or Chandra planeswalkers, so leave it in the sideboard; swap that plan for pure removal and countermagic instead. Anger of the Gods sweeps Elvish Mystic, Llanowar Elves, and Outcaster Trailblazer before they can ramp into Storm the Festival or Cavalier of Thorns, though it won't touch the bigger threats once they land. Spell Snare is weak here since Nykthos Ramp's 2-drops are mostly mana dorks you'd rather kill proactively, so trim it for more interaction against their bombs. Make Disappear is cut since casualty rarely has a good sacrifice target in this matchup and {2} is easy for them to pay once ramped. Prioritize using Indomitable Creativity and removal on Cavalier of Thorns and Storm the Festival hits before they stabilize.