Shades of Darkness

So, it's a side quest. Completing it is not mandatory. Failing the quest deprives the player of a stack of creatures and a stat bonus.

I'm a perfectionist)) I need to complete all the quests)) I'm starting a new playthrough.

Added after 2 hours and 21 minutes
I got the castle, I got 40 Soulless. Here are my questions. Will there be an opportunity to hire more Soulless? Is it worth keeping a garrison in the castle? Is it worth developing another hero? Why is the main archangel a woman all of a sudden? Netflix?))