The existence of Spider Cult necromancers like Arantir and Sveltana comes as a surprise when the introduction to the Necropolis faction in the Ashan continuity was Markal, who is an archetypical megalomaniac with no religious motives whatsoever. Danse Macabre explains it by making him a Nethermancer, who practice Necromancy in a very different way with a very different power source.
In III, if the Summon Boat spell creates a new boat instead of summoning one from elsewhere, it has a weathered appearance with tattered sails, just like a Necropolis boat. When you think of it, it makes sense: it summons a boat from the bottom of the sea!
Before the modern era and modern supply chains (and, in some horrifying cases, even during the modern era with armies led by people who didn't want to bother with supply chains) resupplying and "foraging" for armies meant a whole lot of Rape, Pillage, and Burn to extract money, food or worse from local peasants at swordpoint. So about those caches of treasure and resources your heroes keep "finding"...
The existence of ghouling in the Ashan continuity. Most of the Necropolis's army are reanimated corpses, already-stranded ghosts or high-ranking volunteers like liches and vampires, but making someone into a ghoul is said to permanently remove a soul from the cycle of reincarnation and be the worst punishment that Heresh has. They're common enough to be a core troop class and you get lots more every week. Where are they getting all the victims? How minor of an offense do you have to commit to be one of Heresh's "worst criminals", especially when they need more troops in wartime?
What's more, the Necropolis campaigns are riddled with Path of Blood options (or no option if you're playing as Sandro...) to turn your defeated enemies into ghouls, implying that ghouling gets casually used to eternally damn basically decent people in petty power struggles all the time. Sure, canonically Anastasya turns down the temptation and chooses the Path of Tears, but it's made clear that she's surrounded by people like Ludmilla who have no such scruples. Maybe when the Silver Cities outlawed Necromancy and purged all the members of the Spider Cult they could catch they actually had a point.
