Neobrand assembles its combo through blue spells like Neoform and Planar Genesis, so Mystical Dispute is a cheap, efficient counter to stop the chain before they cheat Griselbrand or Atraxa, Grand Unifier into play. Kolaghan's Command's discard mode forces a discard proactively, or its 2-damage mode closes out the game once they've tapped out. Unholy Heat can't kill their big reanimation or combo targets even at 6 damage with delirium, so it comes out, along with Essence Flux which has no home. Force of Despair stays in since Neoform and Eldritch Evolution both put creatures directly onto the battlefield the turn they're cast, making them live targets.