Isisim Shrine is located in Eldin Canyon, inside of YunoboCo HQ East Cave, under a layer of boulders.

Shrine Location

Isisim Shrine is located at 1842, 2844, 0363, in YunoboCo HQ East Cave under a layer of boulders.

Proving Grounds: In Reverse

If the Constructs in this area see you, several of them will throw time bombs at you. However, you can use Recall to send the bombs back at them, where they will explode near the Constructs and destroy them. They only have a limited number of time bombs, however, so be sure to use Recall on the bombs before the Constructs run out of them. They will start throwing rocks at you when they have run out of time bombs. You can also use Recall on the spinning gears to help you reach the areas with the Constructs.

After they are defeated, go through the gate and open the chest to get a Magic Rod. Then check on the dragon ring to get a Light of Blessing and complete the shrine.