“ A powerful wizard that the PCs encounter is completely silent. He does not speak and cannot be heard as he moves. Even his spells are silent, but his magic is just as potent.
He has a tendency to summon invisible chairs, place foes in invisible boxes of force, and other 'mime tricks'.”
“ A shape-shifter of some sort has taken up a post at the War College of an enemy realm, where he secretly picks off only the most promising officer cadets, arranging bizarre accidents that gradually debase the leadership of the hostile army. In the long run, this will improve his nation's chances when the inevitable conflict comes.
As a shape-shifter he can impersonate superiors and peers alike and send the target candidate to the cleverly-prepared site of his (or her?) execution. As long as he is successful, no-one will ever know about the deception--even necromancy will only implicate the one impersonated...”
“ The Yugzhee, or 'hedgehog-people', guard a great, secret treasure inside their giant burrowed lair. The mysterious Wall of Keys, a 12'x10', foot-thick, cold-iron, 'wall', upon which, on iron hooks, hang 100 ornate iron keys of all shapes and sizes. Each key opens some heretofore un-openable barrier, door, or gate, in the particular game world of choice.
The PCs have come upon a great boon, except for the fact that the keys cease to function properly if separated from the iron wall for more than a few minutes. Higher level characters will be able to figure out how to take the wall 'with them' via magic. Lower level characters will have to get creative.”