What catches my eye is this part, "each linked to some infernal device, half altar, half-guillotine." My guess is this is either the feeding mechanism for the Great Horned Rat or, after building his own God, the Princeps intends to sacrifice it and consume it, ascending himself to divinity in the process. Both are potential options for sabotage at any rate, either through poisoning the nascent deity or preventing the Princeps from sacrificing it.
Could very well also be that he's intending to use 13 (or 12, with him as the 13th) other people as sacrifices in the ritual that he intends to use to catalyze his nascent rat-god into full divine status (while also hijacking its metaphysical architecture in some way that lets him effectively pull a Makuta Teridax gambit and become the god's controlling intelligence). Given that the Skaven in mainline WHFB have a notable number of Verminlord daemons arranged into a Shadow Council that mirrors the actual Council of 13 - or at least that idea's been popular enough that I consider it a decently worthwhile basis to speculate upon - I think it might be a good idea to try to draw up a list of who in the city might be a notable enough figure to be included in this scheme. We can further draw upon a bit of metaknowledge and say that the head of the Moulder brotherhood is likely one of them, as is almost certainly Fafnir Forgefather (if not Skavor himself), and at least three others that could feasibly function as analogues for the founders of the four biggest skaven clans - those being Skryre, Moulder, Pestilens, and Eshin.
Yes, Eshin technically doesn't come fully into existence until they go off on their journey to the east and then return having learned Ninja Rat-Fu, but one of the weapons we were offered was literally an Assassins Creed punch-dagger coated in Ulgu, that's an Eshin weapon if I've ever seen one.
Unfortunately my brain is not cooperating with me enough right now to go through the thread and trawl up enough information to assemble a notable list of who might be accessories to the Princep's scheme of self-made apotheosis, but I'm sure someone's up to it. It'd look something like this:
1. Princeps
2. Moulder head guy (haven't met him)
3. Fafnir/Skavor/something Skavorite-related
4. Skryre-equivalent, I'd suggest looking into the engineers or perhaps the wizards
5. Eshin-equivalent, dunno where this might be. Queen of the ratcatchers was called out as being uncommonly agile and at home in the sewers, so might be our woman
6. Pestilens-equivalent - that Shallayan guy gives me the heebie jeebies
7. Mors (or equivalent upstart clan) analogue: No idea but my gut says someone associated with the Law gods might be it
8. ???
9. ???
10. ???
11. ???
12. ???
13. ???
No idea who the other seats might be for, but given the overall structure of this quest as a demonstration that the whole city of Tylos-Kazvar is rotten to the core, I'm gonna guess that people high up in most if not all the important institutions of the city are gonna be more and more likely to be involved in this - senators and politicians, wizard lords, generals, anyone with a lot of influence.
Hopefully this makes any kind of sense? It's not meant to be at all exhaustive or thorough.
