At some point when near the Copper Coronet, Mazzy will be accosted by Gorf and challenged to a duel. The party goes into the Copper Coronet, talks to Festule, and either buy or refuse the cheat potion he offers. Next, a talk with Surly will lead the party to Bunkin, giving them the opportunity to spike his drink (if they bought the potion) by chatting her up.
So far, so good, but now there are a couple of bugs:
(1) Gorf might fail to show up. This means that the quest cannot complete, though the party can continue on elsewhere. I think what's going on is that Gorf is somehow getting interrupted in his walk-in script.
(2) Assuming that Gorf shows up, Mazzy and he will fight. Once Mazzy knocks him unconscious (assuming that she wins), Mazzy will fail to be teleported from the arena. (Gorf will occasionally wake up and Mazzy can knock him down again, with the same bad result.) Now, the party is trapped, because Mazzy can't leave while she is still part of the party.
I've attached a save demonstrating this. In this save, the party has bought the potion, and is about to talk to Bunkin. Load the save, talk to Bunkin, complement her on her beauty, explain that Gorf has got an ogre brain, offer her a love potion, and then wait. You'll see bug #1 about 50% of the time. Assuming you get past that point: once in the arena, have Mazzy use Strength, and then haste, and then have her beat Gorf unconscious. She'll be stuck after that (and so will the party) -- you'll be at bug #2.