Mystical Dispute is a soft counter (counter target spell unless its controller pays {3}), so it works best when Domain Zoo is tapped low. Despite being a tempo-oriented deck, Zoo does have blue spells: Quantum Riddler, Stubborn Denial and Spell Pierce all let Mystical Dispute cost just {U}. At full price it can still answer Leyline Binding or a key creature, and it gives you a way to interact without falling back on Force of Negation. Brotherhood's End deals 3 damage to each creature and planeswalker, which sweeps away Ragavan and Wild Nacatl, as well as Territorial Kavu while it has three or fewer basic land types (it grows with their domain count and will survive at four or more). It will not touch Scion of Draco or Quantum Riddler, and it also hits your own creatures, so sequence it carefully. Force of Negation only hits noncreature spells, and most of their pressure (Wild Nacatl, Ragavan, Territorial Kavu, Scion of Draco) is creature-based, so it underperforms. Curator of Mysteries is the trim: it is a slow four-mana play here. Lightning Bolt alone won't kill the 4/4, but Tribal Flames with four or more basic land types, or Bolt plus another burn spell, will. Race efficiently and use Brotherhood's End to stabilize against their early board, but be careful using it right before Living End, since Living End returns creature cards from both graveyards, including the ones you just killed.