In a dungeon with wandering monsters, the usual roll for that is a 1 on a d6. The roll generally gets called for once every three turns, or if player characters are especially loud in their actions. But what if the PCs really raise hell? A dungeon-wide escalation die would signify how alert the inhabitants are to the invaders sneaking around and looting their homes. Like in 13th Age, it would be a d6 that starts at 0 and creeps all the way up to 6, the maximum. Then when the DM rolls for a wandering monster, the d6 roll is compared to the current escalation die: if the result is equal to or less than the escalation die, a wandering monster appears.
Increase the Escalation Die if...
- A combat encounter in a monster lair occurs.
- The player characters destroy part of the dungeon (collapsing a room, etc.).
- An alarm is raised (whether by a trap or by the inhabitants).
Decrease the Escalation Die if...
- The player characters retreat from the dungeon.
- They successfully manage to hide and wait it out for a few hours.
- The player characters move up or down a level.
The consequences of the Escalation Die in regards to dungeon encounters will mean that wandering monsters will become more frequent. At Escalation Die 3 and above wandering monsters will appear to be hunting down the player characters, and at Escalation Die 6 the dungeon level will be on high alert. Something like this would probably put the player characters at an extreme disadvantage, but if you're like me and you make wandering monsters a little too easy to negotiate with, a mechanical representation of the 'alertness' of the dungeon denizens might help.