Hello guys :)

The group I DM for in Friday is going to the underdark after finishing a quest.

Spoiler: a quick summary
The aftermath of the quest will be this week, they helped a council to retake control over the country by infeltration and sabotage so the army will be able to enter quickly and take hold over the low quality ruler of the country.

I am searching for ideas for encounters and places, peaceful and hostile.

Any ideas?

I also look for a table I saw in this forum in the past about the state range every CR should have.