Hydroblast is dead here since Replenish runs no red spells or permanents — do not board it in. Annul is excellent, cheaply countering their key enchantments like Attunement, Opalescence, Parallax Wave, or Decree of Silence before they resolve. Aura Flux punishes their enchantment-heavy plan by forcing them to pay upkeep costs on Opalescence, Parallax Wave, and other enchantments or sacrifice them, which is devastating against a deck with many enchantments in play at once. Prioritize countering Replenish itself or the key enabler (Opalescence) on sight, and trim slower cantrips for more proactive answers.