Caged in Stone

The Caged in Stone codex quest is located in Orzammar. It is located in the throne room of the Royal Palace and will only work so long as no king is in power.

Walkthrough
When you go into the Throne room of the Orzemmar Royal Palace, you will see the throne has an information point on it. Looking at this will give you the 'Caged in Stone' codex, which is really a riddle.

You may have noticed that while walking within the Palace there are areas that will create a shifting gears sound. There are three of these, one is in the main area when you come into the Palace at first, the other two are on the west side of the throne room next to each other, each side of a V shape. Position each of your companions on one of these then go and look at the throne again. If you have done this correctly, there will be lightning and a dragon will appear, which you have to slay.

Result
When you kill the dragon, it drops: Ageless (Silverite Greatsword) Heavy Chainmail (Red Steel)