Are your players running roughshod over your monsters and ransacking your dungeons? Are they disrespecting you as a Dungeon Keeper?
DungeonCo here to help, with the handy dandy Horn of Magic Power
The everful horn of a vengeful bull-like creature who wants it back…
A rumour of the knights of some powerful king that sleep until danger threatens the kingdom.
The truth is that they were rebels, trying to split the kingdom. Once captured they were put into an enchanted sleep, protected from age and harm, until their aims have been carried out by others in which case they will awaken.
There is a loophole in the spell in that trying to take one of their weapons will also awaken them.