Ok, if clearing out creeps and leaving combat is a fix then here is the next issue at hand: The neutral monsters spawning seem to be experiancing Fall damage, randomly taking damage while walking / running around. I notice that on the minimap something suddenly turns red while walking around / standing in the tomb. I go up to kill it, run down again, but vailfire still burning and i cannot open the tomb... Now i tried loading a save from 20 hours earlier in the game, and it worked as long as i didnt spawn the guardians. I do NOT want to play 20 hours of the same savefile, picking all the same options in chat, quest, killing etc. so i would be pleased if this could be fixed.
Possible fixes:
Reduce spawn rate
fix the random damage
dont path creatures to close to the tomb (mine is the 4 pillar tomb)
Add an option to unlight touches manually in the game - veilfire can be unlit by waterfalls, maybe let a spell "freeze" the fire, or just hit a switch to unlight them - be creative.
the easy fix is to say: go back 20 hours, but i dont want that. ☹️