The group objects to the possibility of running into their earlier selves, but Princess Viola and her Gnomes already had that figured out. The slide show they present says they are sending the PCs back to 5 days after they left the area.
When they arrive in the past, there is still one Gloom Elf in the tower, but he's in no mood for fighting. He says the Shadow retreated into the large, whirlpool of shadow that now takes up most of the tower, but there was a blockage in it somewhere and he doesn't seem to have gotten where he was going.
With little else to go on, the party jumps in after him. They find themselves (surprisingly) in a prison dungeon, partially flooded, and partially caved in, run by Mole Folk. The mole folk are remarkably lackadaisical about their situation, noting that time runs differently here, but they are reasonably friendly. The dungeon itself is something of a maze with unnatural darkness, so even the mold guards used unspooling twine to help from getting lost. The prisoners are in oubliettes with sort of steampunk contraption doors, set to open when their sentence is up.
Using their hand-held device given to them previously by the Princesses, the party discovers the Shadow is in one of these cells. Waylon is able to pick the locking mechanism, causing the chronometer to run faster, making it open.
The Shadow is inside, and though the part is expecting him to fight them, he is willing to go, even knowing what they are up to. Having had different experiences from the Wizard, he has had a change of heart. He says if they can find "the bridge" located elsewhere in the dungeon, they can get to a place to acquire a page from the Book of Doors that will take them directly to the Wizard's sanctum.
The party sends the Shadow back to the Princesses with a gem. The Shadow suggests the way to find the bridge is to ask the guards. They intend to do just that, but no sooner than they are out of the cell and debating a course of action than a random encounter roll leads to a very ugly bird-beast coming upon them.
At its base, necromancy is the magical art of summoning and controlling shades. It's practice is watched closely by local authorities and the Instrumentality (in those areas where it holds sway). Being able to interact with the shades of the recently deceased is undeniably useful, not the least in forensic necromancy. Where necromancers primarily run afoul of the Instrumentality and temporal authorities is when they use their arts to create undead.
The criminal necromancer creates undead for two primary reasons. The first is for manual labor. These workers don't require a shade in the semblance of any particular person, so necromancers can pluck from the either degraded or partial shades; rudimentary data on physical movements is their primary concern. With a corpse as a substrate and sufficient art applied to their animation, a necromancer can turn out laborers for difficult conditions or troops whose shock value may compensate for their lack of intelligence and skill at arms.
The second application is more lucrative but requires more skill and time. That is the provision of immortality, or as close as their arts may come to it. This requires the creation of a specially made shade, imaged with precision from the current mental vector of the aspiring immortal. In the fallen Latter Age, this generally means destructive mapping of the individual's brain and its functioning. The intellect is then housed in a suitable, durable platform and placed within their old body. The body will inevitably decay, but the necromancer's arts can delay that decay, preserving function perhaps for millennia. The culmination of these techniques is the lich, though botched jobs, and cost- or material-saving techniques have created many other variations, which are more common.