In response to my previous post about Dungeon Keys, FrDave asks: What would this look like with a monster out in the open and what would it look like if those monsters were hidden (in an ambush, for example?)
Basically, monsters or hazards out in the open are listed in the obvious category, and those which are hidden are either in the detail or DM section depending on how easily they could be found.
Here is an example with some goblins and a troll:
The goblins are obvious to a party opening the door to the chapel, where as the obvious detail of the bone covered alter obscures the sleeping troll until it is either looked at in more detail, or the troll wakes up following a battle or other loud noise.
Thoughts? Comments? Refinements?