So you will have to look at it every time party moves from one place to another.
Random encounters tables change a little to mirror the different difficulties PCs are going to confront, since now they're leading a small army.
A new downtime activity is introduced: to create an Underdark outpost, where to rest.
It would be very interesting to test PCs about their skills as leaders. You can involve them in events such as:
- choose lieutenants
- search for spies
- judge disputes among soldiers
- repel an attack to the outpost
The chapter also describes what happens if PCs move towards the places visited in the previous chapters or if they go to Menzoberranzan, the big Drow city.
PCs can go to duergar or svirfneblin cities looking for new recruits for their army.
As for Menzoberranzan you will find obvious that the party can't reach it for now, but some clever PCs could however try to sneakly enter into the city.
Sooner or later PCs, with the help of the map found in chapter 9, will go to Gravehollow, which will be featuerd in the following post.