A guide on how to find and complete the Saas Ko'sah shrine.
How to Reach the Shrine
This shrine is in Hyrule Castle. It might be helpful to activate Central Tower before you look for this shrine.
Hyrule Castle has several black and magenta spires surrounding it. One way to reach this shrine is to go to the northernmost spire and float south from there to the Hyrule Castle area.
When you are in the Hyrule Castle area, your map will only show Hyrule Castle. (You can press X if you need to exit the area and travel somewhere else.) If you are in the north side of the Hyrule Castle area, look for an orange gate on the map that is down at the water level. This entrance leads to the Docks area of Hyrule Castle. In the Docks, go through the passageway to reach a stone platform with a large unlit torch. Light that torch to make this shrine appear.
How to Solve the Shrine
This is a Major Test of Strength shrine, so if you have Guardian weapons and Guardian armor, use those here.