Planar Prison Overview - Baldur's Gate 2
You will only be able to enter the Planar Prison zone during the Rescue Raelis and Haer'Dalis from the Planar Prison side quest. Throughout this zone I strongly recommend you turn AI off as much as possible. While navigating this zone you're going to find that it is very dense in terms of enemies and it will cause characters to run off and attack a far away enemy only to agro more.
To make matters even worse there are teleportation portals on the ground that you can run over which will teleport any character that steps on them to a prison with even more enemies. Slow and steady as well as saving frequently will prevent a lot from going wrong while exploring this dungeon. Within this dungeon our goals are pretty simple, I have laid them out for you below in list format.
1. Go East and take out the Master of Thralls
2. Use the Mastery Orb at the Brazier to set the Thralls free
3. Defeat the Warden
4. Talk to Haer'Dalis
Portals: Throughout this zone you can find little circles like these on the ground that will teleport anyone who steps on them into a prison cell with some enemies. It will teleport 1 party member at a time with a brief delay between teleportation's which will result in some of your party running across the portal and others getting sucked in. These portals are designed to split up your group and have party members fighting in different locations.
Brazier: Once you get the Mastery Orb from the Master of Thralls boss you will want to bring it over to the location marked Brazier on the map above. When you click on the brazier with the Mastery Orb in your inventory it'll break and free all of the Thralls that are still alive throughout this zone.
Master of Thralls: Here you'll find the Master of Thralls with 2 Air Elementals. He'll drop Mastery Orb as well as Staff of Air +2 when you defeat him. You can use the Mastery Orb at the brazier to the south to dispel mind control from all of the Thralls.
Warden: At this location you'll find the Warden of the prison. You'll need to defeat him in order to free Raelis and Haer'Dalis (as well as yourself) from the Planar Prison. It's strongly recommended you take the long route around the Planar Prison and not rush straight for this boss.
Haer'Dalis: Once you've defeated the Warden and made sure that all of the loot is collected head to the northwestern most portion of this area and speak with Raelis or Haer'Dalis. This will begin a brief scene during which everyone gets teleported out of the Planar Prison and lives happily ever after.
Return to Rescue Raelis and Haer'Dalis from the Planar Prison Quest Walkthrough
Return to Free Haer'Dalis from Imprisonment by Mekrath Quest Walkthrough