Special Treasure Area 1 - Brightcrown Canyon Location
Head to the Brightcrown Canyon teleport waypoint, head west/ southwest a little until you reach the object depicted in the Treasure Book.
Special Treasure Challenge 1
This challenge has no time limit and will end when you’re either Frozen three times which will fail it or you defeat the one Cryo Abyss Mage and one Hydro Abyss Mage. Their combination of Elements is perfect to create the Frozen status which is the worst case for this challenge.
The Abyss Mages each have Elemental Shields corresponding with their respective Element, so the Hydro Abyss Mage has a Hydro Shield which is weak to Cryo, whilst the Cryo Abyss Mage has a Cryo Shield which will be weak to Pyro.
Bring one Pyro, one Cryo and one Electro character so you can break their Shields with ease, throw Electro into the mix to create either the Electro-Charged or Superconduct status on them which will either do damage over time or defense down depending which Mage gets hit by it.
To avoid the whole not being Frozen thing, use a Desiccant Potion and a Frosthield Potion to boost your resistances of both Hydro and Cryo by 25% and try to always be dodging, breaking the Mages Shields will cause them to lose their power temporarily, this can be a frustrating battle but persist with it because the rewards make up for it.