The Game Master can use Clocks to keep track of incoming threats in the dungeon. These Danger Clocks should feature a number of section based on the urgency of the threat they represent:
The Game Master may fill a Danger Clock as a consequence of failed Checks, as well as when an event would make the threat more likely, such as when the PCs spend time searching a room, make noise, rest inside the dungeon or draw unwanted attention.
Different Danger Clocks will be triggered by different actions and events, of course — casting a spell might fill an "arcane overload" Clock, while searching a room is unlikely to affect it.
As the Clock fills, the Game Master should foreshadow the incoming danger: once it is completely filled, that threat will become active in full, and the heroes will be forced to deal with it one way or another.