The idea here is that there are very few keyed encounters. Most monsters roam in various zones. Most wandering monsters carry no loot (see description for exceptions), most loot is keyed.
The areas overlap as follows
D20
1-5 no result.
6 overlap. Roll on the least dangerous adjacent area's table. Treat overlaps on that table as no result. If there are less than two overlapping zones, treat as no result.
7-18 add monsters appropriate to the zone the PCs are in. If the population of that monster is eliminated, treat the roll as no result.
19 roll on the events table
20 overlap with most dangerous adjacent table. Treat overlaps on that table as no result. If there are no overlaps, treat as no result.
Checks are made when a zone is entered (even if they step out of the zone and right back in), and once per hour while in that zone, or when combat occurs (at a -5 on the die roll).
Other modifiers
PCs are using a light source (dim) +1
PCs are using a brighter light source +1, stacks with dim light.
PCs are loud +1 (does not include combat, see above. If the PCs argue or the lowest passive stealth is less than 5, this modifier applies. Passive stealth for PF1e is 10 plus total skill/armor check value.
PCs are very loud +1, stacks with loud. DM discretion.
The areas overlap as follows
D20
1-5 no result.
6 overlap. Roll on the least dangerous adjacent area's table. Treat overlaps on that table as no result. If there are less than two overlapping zones, treat as no result.
7-18 add monsters appropriate to the zone the PCs are in. If the population of that monster is eliminated, treat the roll as no result.
19 roll on the events table
20 overlap with most dangerous adjacent table. Treat overlaps on that table as no result. If there are no overlaps, treat as no result.
Checks are made when a zone is entered (even if they step out of the zone and right back in), and once per hour while in that zone, or when combat occurs (at a -5 on the die roll).
Other modifiers
PCs are using a light source (dim) +1
PCs are using a brighter light source +1, stacks with dim light.
PCs are loud +1 (does not include combat, see above. If the PCs argue or the lowest passive stealth is less than 5, this modifier applies. Passive stealth for PF1e is 10 plus total skill/armor check value.
PCs are very loud +1, stacks with loud. DM discretion.