Ryujin
Legend
Also, too much necrotic damage / radiant weakness. My PCs got the bright idea to buy radiant weapons and items that provide necro resistance after P2, and that makes a large portion of this module rather easy. Especially the Nightwalker, which has vulnerability radiant 20.
The Dracolich cleans this up nicely. My character was geared to handle incoming necrotic damage, as were a couple of the others in the party, and we had our butts handed to us quite handily. I didn't have radiant damage, but I did have multiple keywords, and we had a pretty good laser Cleric in the party.
Personally I think that Dracolich is under-leveled, by 3 or 4, in his description. It was a slaughter.