While I don't have anything to add about the Zhents, I'm interested in hearing about your campaign. Where did you place the various parts of RttToEE in Faerun? What deities did you switch? What does the sub-plot with the Zhentarim you're using involve?
some spoilers here for RttToEE...
.
.
.
.
.
.
.
.
.
.
I put the adventure down in the Western Heartlands. Its been some time since I looked at my map but Hommlet is on a minor trade route near Triel (sp?) and the Temple of All Consumption is in the Serpent Hills, about three day's ride north of Soubak. I know this puts major parts of the adventure further away from each other than Monte intended but its worked out fine.
As for gods, I kept Tharizdun the same. IMC he has destroyed the mutliverse several times in the past. This time around, when Shar and Sylune created the mutliverse and the first gods, they also awakened Tharizdun from his long slumber in the void. He tried his old tricks again but was imprisoned. To keep him from being freed, Oghma destroyed the knowlegde of the location of his prison - so even the gods don't know where he is. He has been whispering in the dreams of mortals ever since and has acquired a small cult (but is still a very very obscure deity). When his worshippers created the Cult of the Elder Elemental Eye, he began to aquire power. He launched his plan to free himself. Oghma and some other gods of good moved to stop him but Ao forbade them stating that since it was mortals that were working to free Tharizdun then it must be mortals that stop him. He allowed the gods only to answer questions put to them in the normal fashion (Augury, Divination, etc) and also allowed the gods to set into motion the events that led the heroes to Hommlet.
Iuz has become Garagos (bu the PCs haven't met any of his followers yet.) Zuggtmoy remains herself. The varius temples in Hommlet have just been transfered to the approriate FR god (Ehlonna=Meillikki, etc).
The sub-plot ith the Zhentarim started like this. After the PC's entered the ToAC they lost a character. The player rolled up a new character named Flynn who was a cleric of Gwaeron Windstrom. He had left his family in Baldur's Gate three years ago when he discovered that they were not the worshippers of Waukeen they always claimed to be but rather were secretly worshippers of Bane/Xvim and were working as Zhentarim black market agents. The family (I think of them as a vile version of the Corleone family from "Godfather") were also looking for Flynn's mother (the father having gone through 4 wives) who had fled with a poweful amulet that was important to the family when flynn was only an infant. So, this character (Flynn) finds all of this out one day and leaves home to go look for his mother (and get out of his very nasty household).
To make things more complicated, one of his sisters was a evil and rebelious sorcerer who fled home in a blaze of glory (literally). She bounced around the western part of the realms before she landed a position in an evil cult that fit her personality just right (you guessed it - the Fire Temple in the CRM!)
Then Bane is reborn. The family has served his church well but they have thre black eyes - Flynn, his mother and his sister. they are unable to locate Flynn (because of his amulet of proof against detection) and are also unable to locate his mother. But they DO track his sister down at a volcano in the serpent hills. Three of the older brothers ride out with 40 Zhent adventurers in tow to go kill her.
So, what ends up happening is that the Zhents come to the ToAC and start tearing through the various temples looking for the sister. Meanwhile, the heroes have gone the OTHER direction through the CRM. The two parties eventually meet and the PC's win, though they don't kill the three brothers. In the process of the battle. the Zhents discover that Flynn is there.
The characters eventually take out the Fire Temple and drive the sister off (she flees to the ToEE where she later becomes the consort to Laereth and will be part of the final battle).
The Zhents can't locate Flynn again (Amulet) and decide to take off after the sister again. They aquire reinforcements along the way (sky mages). The PC's will have to deal with these guys at some point.
My players hate the Zhents worse than the followers of Tharizdun. They have actually said, "let's hurry up and save the world so we can go kill those Zhents." So the next adventure will be that.
Oh and thanks for your replies everyone - I plan to use your advice.