After you discover Misko's treasure in the Ancient Columns Cave, you get a clue to the next treasure.

Quest Location

Read the stone tablet in the Ancient Columns Cave to start this quest.

How to Complete the Quest

The clue for this quest is referring to the Coliseum Ruins, southwest of Hyrule Field Skyview Tower.

Thunder Gleeok Strategy

Defeat the Thunder Gleeok in the Coliseum. The Rubber armor set is helpful in this battle. Whenever it shoots beams of lightning at you, you can try to run away to get out of range. To defeat it, you first need to shoot the eyeball of each head until all three heads are stunned. If you have Keese Eyeballs and other eyeballs in your inventory, attach them to arrows to add a homing effect, making it much easier to stun the heads. When all three heads are stunned, the Gleeok will fall to the ground, allowing you to run up to it and hit its heads. As soon as it gets back up, run away, because it will blow gusts of wind at you, knocking you down. When you are at a safe distance, start shooting again.

If it flies partway up in the air, it will spit small lightning orbs at you. Move away from where the orbs are going, to avoid getting hit.

If it is flying higher up in the air, try using Ascend on one of the ledges around the area, then jump off and attach wings to arrows to make them go farther, and shoot at the Gleeok's eyes while falling. If the Gleeok gets too far away, it will cause lightning to strike many places in the ground. Quickly run away from the lightning strikes. Wind gusts will open temporarily where the lightning strikes, so you can try to glide up on a wind gust to get closer to the Gleeok.

Open the Cave

Afterward, go to the south part of the Coliseum and look for the trap door. There are statues near it, and one of the statues does not have a sword. Look for a Rusty Claymore on the ground. Use Ultrahand to pick it up, rotate it to point downward, and push it toward the statue without a sword. The sword will move into the statue's hands and the trap door will open, allowing you to enter the Coliseum Ruins Cave. Open the treasure chest in the cave to complete this quest.