Overlooking the Complex

Without the assistance of the copper dragon, the party must locate the valley with the cultist' compound in it. The trail they are following runs to the northwest into the steepest spires of the Iron Teeth massed to the west. It is a feeder trail for the slaad, in particular, although other trade between the Iron Teeth and the giant strongholds of the eastern mountains has used this route long before the slaad arrived.

The valley of the cultists is not easy to find, but even a reasonable perception roll (DC15), or survival roll will note an eerie watchfulness to the north of the trail as the party passes the valley to its south. There is not a visible route toward the valley, they will need to move across country to get there, but the sense is palpable enough that they won't miss the valley, but making them roll until they are successful can give a location to send them into the valley from.

I think five points should be enough to be interesting (I'll add entry points to the map I sketched and include it again). The first point is early awareness, and allows choice over the first two points noted on the map. Successive rolls move the entry further along, with anything more than five bringing them to the final access point on the map. If the number of failed attempts is too great (say, seven or more), have them locate the final access point but at nightfall, rather than mid-afternoon. This will force them into the mountains at night, or to make camp before entering and exploring the valley, causing its own worries and a night encounter from something. All of which increases the chance of discovery and the likelihood of raising an alarm within the cultist complex.

Access point one brings the party into a high pass that gives them a chance to notice all of the patrols on the mountainside. They can then decide the approach they wish to use to enter the valley. They notice the regular guards on a perception (DC14) and the secret patrol on a perception (DC20). Survival can also be substituted for perception for anyone skilled in it. Access points 4 and 5 are on the far side of the valley, which has steep, difficult paths to negotiate. With successful stealth/survival rolls (DC20), they can avoid detection and reach the guard outpost on the isolated spine, but they still are separated from the main complex.