31Y TOOTH VAULT. This large chamber has a ceiling height of about twenty feet, but beyond the ledge the depth of the chamber is at least fifty feet (the gray area). Millions of children's teeth fill the floor of the vault and falling in would result in 4d6 damage (the teeth break the fall a bit) and conceivably drowning damage. Suspended from an iron chain is a spherical cage holding a giant white mouse.
The mouse is Topolino, the spirit that gives silver coins in return for children's teeth.
Topolino (AC 5; MV 12”; HD 7; hp 34; #AT 1 bite; D 1-10; SA Spell-like abilities; XP 847)
Topolino can perform the following magical abilities: shrink to normal mouse size and back, cough up a silver spanner (when he takes a tooth from a child's pillow only), assume gaseous form, and forget. He has the class abilities of a 20th level human thief. Topolino is neutral good in alignment, gentle and non-violent. His cage (made from magicked silver and worth 10000 gold crescents) negates his special abilities.
If freed, Topolino will grant a boon to the adventurers. They may ask of him anything that is in his power and he will try to help. What this entails and how this play out is left to the discretion of the Dungeon Master.