There are ruins, scattered about the world, and all are sealed with unbreakable locks.
When all of these locks suddenly open, what emerges?
A cave with weapons sunken into the walls, blades sticking out of the floor and ceiling, and so on. Possibly, any weapon used in it could be torn out of the hand and sink into the stone.
It is possible to buy magical abilities. The process is very dangerous though, involving chemicals, rituals and surgery possibly leaving the aspiring mage insane, retarded or scarred for life.