In reading through session 4, it seems to me that there is a very good possiblility that the adventurers will avoid combat altogether. As a back-up, I am planning fun combat encounter for them. Looking at the Building Combat Encounters section of the DM Guidelines, I've decided that after Barcero and his cronies clear out, a fight between the party and two trolls that have recently claimed the ruins as their own might be a fun encounter to run. Trolls have lots of fun mechanics with their customization options and it will give the PC's something different than the same old Orc/Human encounters. Two of them look like a good challenge for a group of Five 5th level PC's, with an average encounter being around 250 each, (1250 total). Two trolls is 1220. Add in the customization options and it could be fun.