Go to the lake relay south of Hyrule then go to meet Shimina who will expose you to a thorny problem: the lightning keeps falling on the relay and she is scared to death. To soothe it, climb on the roof of the building and remove the sword that made lightning strike. Shimina will offer you the insulating helmet to reward your efforts.
Armor: Sanctuary of Toh Yahsa
For the armor, you will have to solve a riddle in the eastern region of Hyrule. Go to the point shown in the pictures below, then observe the stone monument in the middle of the lightning-stricken valley. You must bring 4 colored orbs and put them in each of their statues. Problem: It is constantly raining and several orbs are high up. The easiest method is still to uncheck 1 or 2 arrows in the spheres to make them fall off their pedestal. To send them to the stone monument where the holes are located, find a slope steep enough, apply cinétis to the sphere and hit it hard enough to blow it up in the right place.
Boots: Blessing of Qukah Nata
Again, it is simply a sanctuary that rewards your efforts to find its entrance. Go south of the prelude plateau, then place an iron weapon on the top of the rock in stormy weather, which you will find at the location shown in the images below. The lightning will strike the object, destroy the rock and free the entrance.
Written by Bastien "Lloyd" Dubosq-Luyer. Translated from French by Millenium.us.org.
