Tension

Tension is, broadly speaking, how dangerous the game determines your current situation to be. This is automatically calculated based on a number of factors including number of enemies, strength of enemies, and current player status.

Several different in game mechanics work based on tension. For instance Xom is both more likely to act and to act positively when tension is high. Likewise the Demonspawn's demonic guardian will only see fit to spawn if tension is high enough, vanishing again once it determines the situation to have settled down.