The Worst Feast
Okay, you get the 10 Pretty Good Spells spellbook.
Moth's Detect Magic: Well, my memory's pretty bad of what I give you guys, so if I miss something, remind me. The spellbook and chess piece are magical. Keys are not, ruby ring is not.
Spells in the book:
Sleep
Charm Person
Invisibility
ESP
Fireball
Dispel Magic
Ice Storm
Polymorph Other
Contact Other Plane
Cone of Cold
At some point you can ID the chess piece. It's remarkably non-descript for a chessman, combining qualities of bishop, king, and pawn. You ID it and learn it's the Chessman of RuyLopez, a powerful strategist from another dimension. If you throw it on the ground and yell "RUYLOPEZ", he'll arrive for 64 rounds. Grant each of you +3 to hit, dmg, AC, and saving throws as he coordinates your master strategy. Of course, Ruy himself is AC 10 with 8 hp, so be careful with the guy. One use only.
The gems are 500 gp each, and the ring is a fat 4000 gp.
...
Up to level eight, the Queen's chambers.
This level is even more lavish than that below. Metallics and soft hues swirl in beautiful Southern marble. Frescoes depict decadent scenes of banquets, parties, gardens and pastoral views, maidens and shepherds and that kind of stuff. Sniff, sniff. It smells of lavender in here.
And foulness, as you push open a purplish set of double doors, revealing a gigantic feast hall. A long table dominates the room, covered in what was once a magnificent banquet, but all the food has gone to rot. If 'food' it once was... you see corpses dressed and arranged for the eating on the table itself, a platter piled high with rotting entrails, a beautiful gold goblet filled with feces. And so on.
At the end of the table awaits the hideous Queen of Greyhelm. Everyone make a save vs. spells.