from memory i think that Festule turns up at the C.Coronet during the duels or the Mazzy/Gorf the Squisher battle. I think you can give him his potion back then for some XP. i seem to remember doing this bit but it was a long long time ago. Maybe someone else can be more specific.
------------------
It's bleedin dark down here, slippery too.
Man, that's a pisser.
