It is the last chapter, where the campaign plot comes to an end.
The Dark Heart has been created (by Vizeran or whoever else), placed in Menzoberranzan (or another location) and its power starts to call there the Demons.
They start to fight among themselves and when one of them dies during the furious battle its essence comes back to the Abyss.
The last survivor, presumibly badly wounded and weakened, will be killed by the players and sent back to the Abyss too.
If all goes well then the PCs can rejoice and be rewarded as true heroes.
I like a lot the final chapter because it's full of rules, hints and suggestions letting any DM to build his own version of the last battle, according to the flavour of the own campaign and the players' own tastes.
You can focus on moral dilemmas or create a struggle with Vizeran, or have a lot of fight against minor demons and many other options.
You can even let your players role the Demons fighting each other.
I'll do it!! For sure!!!
The chapter has a page for further developments of the campaign, using the unsloved plots of Out of the Abyss, such as:
- What was the goal of Lolth's plan?
- Will she try to get her revenge?
- Where did Gromph Baenre go?
- If Menzoberranzan is destroyed where will the survivor Drow go?
- What will be of Vizeran?
- Vizeran makes an appearence also in the adventure Princes of the Apocalypse. Will he be a "great villain" of the Forgotten Realms??
- What will happen if one Demons or more aren't turned into the Abyss?
The review has come to an end.
I hope you found useful this humble work.