This is about a simple mod that provides light in dark areas of the game.
Here is the Ampelian cave normally:
And after turning on the Bulb:
Notice the skill in 7th slot. What the mod does is, it adds one unlocked skill, named Bulb, to all mastery. As soon as you select mastery at level 8 you'll get to equip the Bulb skill in one of the slots at the bottom. When you use the skill it creates a light source above character's head, and it starts emitting light over 100 meter radius.
Here is how you select the Bulb:
For download and more details :
https://titanquestfans.net/index.php?topic=485.0