Upon reaching the Selunite Outpost in the Underdark, you find yourself in a secure stronghold that has been abandoned.
It seems that the outpost gate is still secure as it is locked and even protected by a magical defense that must have been set up a long time ago.
While opening the gate may have given others an issue at first, opening the main gate can be done effortlessly if you take a closer look at things.
How To Disable Selunite Outpost Defenses?
You will notice that the gate is protected by magic and if you approach the front, a Minotaur will attempt to attack the gate but gets blasted.
The same will happen to you if you stand outside of the gate when the defenses are still up, which makes it necessary to deactivate them unless you go around.
To do this, you simply need to target the Moonstone on top of the statue that is sending out beams to both defenses and hit it with a ranged attack. (Bow or Crossbow)
How To Open Portcullis?
Once you have taken down the defenses, you can now safely open the gate and step outside of the Selunite Outpost after lowering the Portcullis.
This can be done by approaching the Portcullis (Gate) and checking the right side for a lever, which you may interact with. (It is behind the Iron Candelabrum)
Keep in mind that once the defenses are down, enemies can still run after you, and you should be prepared to fight them off.
Opening Gate from Outside
If you are coming from within the Underdark and need to make your way into the Selunite Outpost, there is a broken section to the side.
You can reach it from the lower part of the Underdark but along the way, a Spectator will appear and attack you. (It will control the Petrified Drow to attack you during the fight)
Verdict
Making your way to the Selunite Outpost is best done by taking the route from the Defiled Temple as it is much safer.
You should activate the waypoint in the Selunite Outpost to ensure you have a way to travel to it whenever you leave.
Keeping the defenses on and using the broken section can be time-consuming and it is best if you just turn them off and open the gate.