I am currently running this campaign for my group. I have made some changes to the module:
1. Auril is trying to make Icewind Dale into a Domain of Dread a la Ravenloft Campaign Setting. She has cordened of the region with a deadly freezing mist. She is trying to escape Toril becsuse her power was diminished by Umberlee, and Talos and lart of her essence was trapped in an artifact known as The Ring Of Winter (See: Tomb of Annihilation).
2. The Duergar Leader, Xardarok Sunblight, is a paraplegic, and has a flying Combat Wheelchair.
3. The Town Speaker of Bryn Shander Duvessa Shane, and the Sherriff Markham Southwell were leaders of a cult of Beshaba. They intended to bleed the town dry by using the “lottery” to sacrifice people to Auril and confiscate their belonging and wealth. They planned to abscond with the wealth. Unfortunately, they found out too late that no one was getting out of the Dale.
Shane and Southwell had an agreement with the killer Sephek Kaltro, who would ensure the sacrifices were dedicated to Auril. But when he found out they wanted tk leave, he i formed them that he would lersonally hunt them down and “dedicate their souls to Auril” if they tried. Thus they put the bounty out on Sephek.
Some of the Gods of Toril have taken an interest in Auril’s plan. Umberlee and Talos want her gone so one of them can assume the role of the god of winter, and thus increase their power.
Helm, Lathander, Bahamut, and Sylvanus want to stop Auril, and if possible restore her to her old position as God of Winter. To return everything to normal. They are trying to use the PC’s as their pawns.
The god Mask is offended that Auril is trying to “steal” a piece of Faerûn, and is trying to foil her plans on principle.
Asmodeus wants to see Auril dead so he can assume her power and become an even stronger diety. Levistus works against Asmodeus’ ends to take that power for himself.
The PC’s have freedom of choice to solve this however they want. I am not emotionally attached to the outcome.