Great, mysterious chambers hidden deep in the earth beneath that enigmatic city of Stoneholt!
The city of Stoneholt is generally considered one of the Wonders of the World, but it conceals a second wonder - a labyrinth of massive sewers and storm drains greater then anything man has built.
What if a mage passes his powers on to his firstborn son, and a female mage to her first daughter, leaving the parent POWERLESS? A plain mortal, a sorcerer no longer, all wizardly might gone?
Or: what if a female wizard recieves the power of a mage who sires a child with her? Could lead to promiscuous witches and overly careful mages.