Mount Gagazet Cave

The Sanctuary Keeper's opening move is Photon Wings, which deals damage and inflicts Curse, preventing Overdrive use for both characters and Aeons. Curse can be removed with Dispel or Holy Water. Photon Wings can also inflict Confusion, Darkness, Silence, and Sleep. To mitigate this, summon an Aeon to take the initial hit.

After Photon Wings, the boss uses two normal attacks, followed by Mana Breath, which targets a single character.

The boss can cast Protect if Armor Break is used on it. Conversely, inflicting Darkness or Poison may cause it to use Esuna to remove those status effects. If Reflect is cast on the boss, it may cast Reflect on one of your characters, bouncing spells back onto itself.

Sanctuary Keeper can use Curaga to heal itself and Regen, which should be Dispelled.

As you attack, the boss may counter with Tail Sweep, which deals damage, delays turns, and removes Haste.

If you inflict Slow on the boss, it will counter by casting Haste on itself.

Use the initial script-driven phase to set up buffs for your party. A Mighty Guard variant (Rikku Mix) or Kimahri's Mighty Guard Ronso Rage is recommended.

Consider casting Reflect on the boss to prevent it from buffing itself. While Reflect is active, use an item like a Silver Hourglass to inflict Slow, which can cause the boss to enter a loop of casting Haste on itself.

Shiva's Heavenly Strike inflicts Threaten, which the boss is not immune to.

After defeating the boss, follow the trail behind it to trigger a scene, then interact with the sphere on the ground. Continue forward for another scene, leading to the exit to Zanarkand.