Ability to choose an enemy type (or maybe environment type, or both) and some way to choose difficulty of encounter and generate an encounter based on that info.
Example, choosing "Underground" and "12 hit dice" could generate an encounter like so:
Boss: 1 Aboleth (8hd)
Minions: 4 Darkmantle (1hd)
The HD would "add up" to 12 hit dice, and all the creature as suitable for underground combat.
Ability to choose an enemy type (or maybe environment type, or both) and some way to choose difficulty of encounter and generate an encounter based on that info.
Example, choosing "Underground" and "12 hit dice" could generate an encounter like so:
Boss: 1 Aboleth (8hd) Minions: 4 Darkmantle (1hd)
The HD would "add up" to 12 hit dice, and all the creature as suitable for underground combat.