Hey all.... did some googling and only found forums topics where people were TRYING to bug Duriel.

Of all bosses not to get credit for... I've killed him twice now while having the quest. My character was actually in the Duriel room when he was killed. Do I have to do damage or something instead of 100% by my rusher? God, it's been a while....

Any help would be much appreciated. Decades of playing this game and never came across this that I remember.

you dont even need to be in the room, you can be sitting in Lut Gholein while others who need the quest kill him and you will get the quest

Hi,

did you go talk to tyrael once duriel is dead?

Normally the quest turns into "explore room" or something like that. The quest didn't even change. But crap, I probably should do that anyways and see if it works. UGH. Thanks guys. Gonna try when I get home and report back.

while self-rushing myself, I already had 'quest cannot be completed', cuz the merc of my rusher kill normal duriel before i enter with the rushed char, then went talk to Tyrael & resume the quest (he open the portal and yu have to talk to Jeyhrin),so it may solve your issue