Still bugged. Two weeks after launch.
Same on EU Kantia, but after 3rd try instead of resetting he just disappeared and he hast spawned for hours. We cant continue with questline please fix it 
Same problem.
Spent all day yesterday doing my weapon quest and get to this step and the boss just keeps resetting no matter where I tried to fight him.
It also has a terrible melee hitbox where his legs block and push you around but your swings don’t hit him and do damage.
This issue is still persisting today on US East Server Frislandia.
Trying to get a group together to 
the boss against the wall, as it appears in the video above, is very difficult. It is hard to reliably recreate the fight and get the kill to progress the epic weapon quest.
Is there anyone here that can update anyone on the status of this bug?
Today i killed him its just you need only enough people thats all. And the agrro ez.
Yep same on Inferni server .
Yep, still broken.
Still broken! Boss does not spawn. Waited 45mins after I assumed he had been killed previously. 
Broken on Phlegethon. MOBs tether is too short and he rubberbands and resets constantly. Almost impossible to do with the size party intended.
It’s been 22 days, can you fix it already? This game looks like a very bad beta from an indie company
Boss is still bugged. Can we get a fix like yesterday please, ffs
Actually just managed to kill it despite the bug. However, it does not give any drops or quest rewards. Been broken for 1 month apparently. I Guess it is impossible to get that 580 sword, ty for wasting 4-5 hours on it.
Tried to kill it for 1 hour now with a 5 man. Boss constantly resets even if he is right on top of his spawn, for no reason at all. Killing the tentacle first also instantly despawns mozrul.
same
I finished the 580 GS sword line and defeated mozrul. It’s hard because he resets but not impossible. Got all the drops and finished the quest when I did. Use heavy attacks to break his stamina and then burn him down with two groups when he kneels.
Killed him easy with a group of 4.
Solution:
- The tank just stands on the Ore and aggro the boss, and he won’t reset
Bugged! Please fix!!
Just hit this quest and yea I’m stuck on it too, he keeps resetting
Still bugged, he is resetting after 10-15 seconds
bugged every where…
but i will try this ore solution 
still broken wtf, wasted hours doing the quest line, to get kicked in the nuts, over what should be one of your questing highlights, you worked so hard to reach the grail only to have AGS say fuck you.