The Mage's Apprentice - Act 3 Side Quest
Location: Cave near Darthrul
Closest Portal: City of Darthrul
Objective: Solve a Mirror Puzzle
Reward: Random Loot & Gold (if you solve the second puzzle)
The Mage's Apprentice begins by speaking with Mage Boden in Kalrathia (Act 3). Boden asks you to find his apprentice who ran off to the Eastern Plain of Tears in a cave nearby the City of Darthrul. What you'll need to do for this quest is to teleport over to the City of Darthrul then travel through the ditch near Darthrul to reach the cave that this quest takes place in. Near the bridge that takes you into Darthrul there will be a path into the ditch close by; follow the ditch to the southwest to find the entrance to this cave.
Inside of this cave you'll find a mirror puzzle that operates the same way The Lost Azunite Artifact Story Quest puzzle did. You will need to place the Golden Mirror in the statue without a mirror and then rotate the correct statues to point the light at one of the two doors in the room. One door has Mage Apprentice Darek inside of it (Boden's Apprentice) and the other door has the treasure.
Below are screenshots that will show you how to solve this puzzle along with a video I have created for the same purpose. Check out my The Mage's Apprentice Puzzle Solutions Youtube Video if you prefer videos for these sorts of things. Otherwise, I have included two screenshots below which will show you both puzzle solutions. The first one will lead you to Mage Apprentice Darek and the second will open the door to the treasure vault.
When you speak to Mage Apprentice Darek he will tell you that Mage Boden has been working with the Morden which is going to lead us to an inevitable confrontation with Boden back in Kalrathia. After collecting the treasure and speaking with Darek inside of this cave you'll want to return to town where you'll confront Boden.
Boden will attack you after you call him out on his evil deeds but he's pretty easy to defeat. I always find it humorous how the other NPCs do nothing and don't react at all to the situation. Darek will walk in after Boden has been slain and you will be able to turn the quest in to him and complete it.