This was the last part of the trilogy for the second tier of the 7th season. Although I liked the adventure, and it provided a great potential for in-character motivation of the main villain (I chose to roleplay him as a druid that has gone mad after being unable to raise his son from the dead, so he sealed a pact with some entity: better raise as an undead, than not to resurrect at all), the villain itself was pretty weak mechanically. I have an experienced group, but a druid simply doesn't have as much offensive spell as the other casters have. Also, I think that the base spell selection for the boss is pretty disastrous for him. Also, now when Xanathar's guide is known, some spells should be taken from that book, because they provide real challenge for the parties: CRs given for the NPCs do not take powerful magical items in account. But overall, the adventure is very well-written and is fun to run.