I believe there are two ways for a necromancer to reasonably fake their own death. One way is to do what Corpsetaker did to Captain Lucio. Pull a body switch during a fight an instant before the enemy strikes a fatal blow, or some variation of that move involving a body swap. The second way to fake a death is what Alt-Harry is doing in the Mirror Mirror world; summoning almost identical copies of himself from other realities and leaving them in a position where an enemy like the White Council kills the copy while the original gets away.
I don't know this second method requires a necromancer to pull off. However, I suspect this second method is how Kemmler kept coming back from the dead. He was summoning other Kemmlers and allowed the White Council to kill them in order take the heat off of himself. This created the illusion that Kemmler came back from the dead multiple times.
I think a third method, Corpestaker's soul hanging around after it's body has died and possessing another person, is just an edge case.
I should never have mentioned the necromancers or Justin. Derailed the whole topic lol.
I think the methods work out, although as you say I'm not convinced necromancy is required to bring counterparts from other universes. Whose to say that Kemmler didn't use a mix of techniques? He isn't Harry, why stick to the one trick? By all accounts he was a brilliant innovator. He literally wrote five books full of magical knowledge. He is in the order of the original Merlin I'd say. Monstrous of course. But very, very brilliant.
The third case actually seems like something he didn't do initially, and almost seems like something stolen directly from Warhammer with Nagash (which is where Jim got the name for Kemmler, amongst other things). Nagash is the first and greatest necromancer in the Warhammer universe, he invented it. Every time he is killed he hangs around in the spirit world and waits for the equivalent of Halloween (called Geheimesnacht in Warhammer) and then returns, and then gets killed again.
It wouldn't surprise me AT ALL, if Kemmler was using a similar trick, or if he hadn't already.
The third method is not about faking your dead, it is about returning from dead and it is a very necromancy way of doing things. I think that is what Kemmler did.
Well, it's not that black and white. If everyone believe Kemmler gone for good then it is very much like faking a death...by actually dying. A matter of semantics as it achieves the same end for Kemmler: he gets to hide in the shadows and manipulate things while everyone else thinks he is gone.
Now, in the Chronicles of Amber by Roger Zelazny there are a number of characters who are essentially planewalkers. They cross into the "Shadows" which are the various possible universes created between Amber and the Courts of Chaos (the two poles of reality). The closer a Shadow is to Amber, the more ordered and more similar it is to Amber (Amber is the world of order). The same applies as Shadows get closer to the Courts of Chaos. There is some debate to whether the being walking into a Shadow creates that universe around them, or whether that universe was there to begin with. I believe it's a bit of a quantum entanglement issue myself, that is something that cannot be measured unless it is viewed and the viewing of it changes it. I suspect Zelazny was using that sort of idea (despite that science being relatively unknown at the time).
Anyway, in the Amber Chronicles a character called Caine literally does the whole summon a copy of himself to get murdered trick.
Now we know Jim is a big fan of the Chronicles of Amber, we know that he uses elements of it - like the scene where Harry and co. travel through the various Ways, or the White Court (which are based on Chaos creatures created in AmberMUSH, which was a roleplaying game of Amber in the 90s). He also said he had to reread it again before Peace Talks and Battle Ground, as he needed to work some stuff out.
So I'd say there is a good chance we will see more of stuff connected to Amber.
