In the caves just after the two white wyrms, there are some duergar campament, supossedly you have a quest there. You have to kill every monster in the area, includind a shambling mole and some jellies, but I´ve killed ALL including those annoying fire beetles,and... NOTHING HAPPENS.
Where did I go wrong? Please, I need some answers
(just to make it public, in the normal mode never happens this, just in the HoF mode)

Many people have had this problem. It's either a bug, or there is still one fire beetle floating around, or there is some problem with the order in which you kill things and/or talk to the Grey Dwarves.

IWD2 was sooooo buggy
it bugged me
HAW!!!

If your cheat console is activated, type in the following:
ctrlaltdelete:SetGlobal("AR5101_MONSTERS_DEAD","GLOBAL",2)

or set the global with an editor.

Thanks, that was usefull