I brought all the artifacts to Phil Necromancer, he sent my soul to hell and gave me all the instructions, but nothing happens. How do I get there?

Similar problem!
In my case, I suspect it's Miranda - I didn't befriend her in time, and at the beginning, I completely cleared the entire map. And now, even though she's under my flag, she refuses to be in the same party as the main hero - it immediately results in a loss. Could this have been one of the conditions for triggering the script? I've searched through the entire campaign editor, but found nothing...
How about you, did you complete her quest?

Added later:
Through trial and error, it was discovered that if you start over and follow the instructions exactly, without getting distracted by exploring the map, the teleportation to Hell works.
As for Miranda in my case - (fortunately, I had saves from different stages) if you combine her with the hero in one party BEFORE delivering the book to the mage's tower, her quest is successful, - BUT the necromancer still doesn't teleport us anywhere.
It seems I'll have to play through it again =[/COLOR]