This page of our guide to Biomutant features a walkthrough of the side quest The Lumentower. We have described everything you need to do in order to complete the quest and earn the rewards.
Starting the quest
How to start: Enter the lighthouse.
Reward: 100 XP.
Activating the beacon
Activating the beacon is simple. You just have to use the stairs and ladders to get to the top - there's nothing tricky here.
Once you're at the very top, approach the device and set it in motion. This is how you will activate the light.
Following the light
The lighthouse will light the entrance to the cave for you. It's not very far away, you just have to swim across the reservoir and then climb to the top of the mountain. There you will see the glowing inscriptions on a rock. As you get closer, you will open an entrance to the cave.
In the cave, you will have to fight an enemy who guards the treasure. Eliminate him so you can keep going and continue the quest.
Pri Murgel Sword
A sword is waiting in the middle of the cave - the Pri Murgel Sword. This is a great weapon, not only does it do a lot of damage but it also sets enemies on fire.
To get to the weapon, you'll need to examine more glowing rocks - do this by going from left to right.
Once you have examined the walls, the sword will unlock and you will be able to put it in your inventory.