Another awesome update
@torroar
I was wondering if anyone could help me understand, or point me at posts that explain this:
So, is Dark Magic unique in that it can be harvested, and more importantly is the magic harvested finite and thus stored in phylacteries and dark artifacts for later use, or added to the user's own being somehow? I know of course the general concepts of Wind of Magic manipulation, so I'm guessing it's the former, with the latter often the provenance of rituals that change the user and inflict Marks and even make into oneself an Incarnate, like what Zacharias attempted so long ago.
Not to mention Kemmler's own ritual:
To answer this a bit more from my own stuff, magic can be stored and utilized at various times, yes. It's not really a super common place sort of thing, but for all of Warhammer there's been notes and ideas and efforts to channel and dispel magic, basically manipulating the Winds back and forth from around. There are, as well, spells which can restore the body and mind, fortifying them, in various fashions. Most Necromancy spells are generally built around summoning undead and empowering them, sure, but the Black Art is technically capable of other strange stuff.
Much like how Von Tarnus is a famous and incredibly capable enchanter and creator of magical items which are used centuries later despite being a Bright Wizard and former Carroburg Greatsword - you'd usually expect the Gold Wizards to make the fanciest enchanted magic gear for the most part - Necromancy is capable of doing more than 'just' the spells described in Realms of Sorcery or Night's Dark Masters. There are little notes here and there for 'spell creation' and 'not an exhaustive list' and so on when it comes to the Lores. For the Black Art, you've got stuff like Father W'soran's Architect which is a dread raising of a fully made wizard tower for a necromancer, the Rebirth in Blood for vampires, and so on and so forth.
To make it even more explicit, there is the TT Lore Attribute of The Curse of Undeath, described as such:
As the powers of Dark Magic are wielded to the purpose of necromancy, its unwholesome energies animate and invigorate the Undead - When a spell from the Lore of the Vampires is successfully cast, the Wizard (or another friendly model within 12'') instantly recovers a single Wound lost earlier in the battle.
And also The Signature Spell of the Lore, the 'Invocation of Nehek' described as:
The caster intones the dread syllables handed down from Nagash himself, breathing unlife into the cadavers strewn across the battlefield. - I'm just gonna summarize here, but the spell restores a number of wounds of D6 plus Wizard level, with some other stuff.
But, basically, for a being who is so enshrouded with Undeath as a necromancer, a channeling of such sorts of things can also heal them. For the purposes of spells like these, those like Heinrich Kemmler are essentially treated as undead themselves, you get what I mean? Therefore, by gathering together powerful Dhar wells, it would allow Heinrich to then channel said energies for his own purposes. In this case, restoring himself and fortifying himself steadily over time after his near death at the hands of Arnaud. I'm not saying he's doing or has done anything as the same as the aforementioned Gilded Body thing, but we can actually leap horizontally to TTWW, with Mannfred's little pet project in Helman Ghorst, with parts of his talent tree mentioning how his grasp of the dark arts has imbued him with strength clearly beyond his frame and also unnaturally caused his skin and flesh to harden to make otherwise fatal blows sorta bounce off.
Additionally, it's generally noted that the more a necromancer studies necromancy, channels the magic, does their studies, increases their grasp and capabilities through experience, they grow more powerful. Just sorta how that kind of thing works, the more you know = the more you know and also knowledge = power. Especially when it comes to magic.
Then you have objects like the Mortis Engines, basically big mobile shrines of necromantic energy. Usually with powerful necromantic remains from Liche Lords or Master Necromancers and the like. The effect they have is described as such:
opens the lead-lined reliquary, the deadly artefact within can be held aloft, leeching enemies' life energy away and invigorating any nearby Undead creatures. The longer a battle rages, the more energies the relic absorbs, and the more powerful it becomes. Mortis Engines can typically be found where the fighting is thickest, ominously drifting into bloody battle lines. Such positions simultaneously fuel the Engine with the energies of the dying and allow the engine to support Undead forces where the fighting is thickest
So, literally, having enough objects and things infused with necromantic energies is basically a radiating object of power, passively supplementing and providing further strength for the undead and those who are sorta close to it. Ghouls and necromancers are both still breathing, sure, but they count enough as undead to be similarly invigorated going by every measure I can determine. It's obviously still dangerous, fraught with issues, and if a slightest instability occurs that cannot be dealt with the whole Mortis Engine can tear itself apart from the stuff it's carrying interacting with the Winds in flux, but the point is that it is capable of doing such things.
Some reliquaries also carry blasphemous tomes to battle, or scrolls of parchment rumoured to have been penned by the Great Necromancer Nagash himself. Often the Winds of Magic become nigh uncontrollable when such a fell tome is near. Heavy with evil magics, these tomes are painstakingly illuminated with such effort that often their creators' souls themselves are inked upon the parchments of Human skin. In battle, these books can be a boon to the twisted practitioners of necromancy, but also the bane of reckless and inexperienced spellcasters that would dare to risk relying upon such diabolical relics.
As a result, there is actual impetus for Heinrich Kemmler and others like him to liberally scour crypts, tombs, boneyards, ossuaries, graveyards, mass graves, sites of terrible battles, etc. for objects which for one reason or another are suffused with Dhar energies. Because if they get them, and can channel/contain/use them properly, they are sorta like, I dunno, batteries or whatever that can be of great aid. Hence grabbing trinkets, old swords, remains, heck a brick or two from Mourkain's ruins or the ruins of Vorag's fortress which for one reason or another became a lodestone, because they can be used for the purposes of a necromancer with the knowledge to draw from them. Which, being the bearer of the great majority of Mannfred von Carstein's personal library assembled pre-3rd Vampire War, multiple Books of Nagash, etc., Heinrich is one of said individuals with said knowledge.
Sort of like how the Arcane Battle Altars of the Magic Colleges literally act as magic loci, and add more dice to your pools that you do magic stuff with. Objects powerful enough with the Winds of Magic can be boosters, one way or another, you just have to be able to utilize them properly.
Additionally, though, I'd note that Kemmler is basically always studying, always researching, poring through his tomes and Books of Nagash, learning all the while. He was just thoroughly wiped and damaged from his battle with Arnaud. So, basically, once he'd fixed himself, it was not him returning to his pre-Arnaud strength, but rather he reached the level he was already at, simply without the massive debuff left behind by the Liche.
Does that make sense?