Aside from the obvious example that are Discipline Priests, I’d like to state I am talking about the internal wielding of each rather than external like Priests do, which is also why (presumably), they aren’t nearly as affected by shadow.
We know that Death Knights can wield like (Sir Zeliek being so extensively devout to the light that he retains some of his will under the Lich King’s tight grasp as a horseman aswell as his ability to call on the light)
Aswell as Forsaken for the same reason (Though they do appear to hurt themselves in the process.)
For example, let’s take a living normal being with no unique effects of their own. A human. Instead of infusing him entirely with light, let’s take a seed of light and a seed of shadow. How do we think it’ll react? Will the seeds still be so potent as to war with each other and kill the user? Will they be stagnant and unable to even do a single thing? That’s what I’d like to know.
I’m working on a bit of a concept and find that having outside perspective can help on settling such matters ontop of personal research. Let’s do some brainstorming shall we?
Sir Zeliek is the big exception to the rule of death knights and the Light. He is a one-off example, an exception to the norm and should not be considered as a full example of Death Knights being able to use the Light.
Arguably depends on what you mean by a “seed” of either cosmological force.
To me, a seed implies something dormant that hasn’t come into fruition, only containing the potential to be realized under the right set of circumstances. In which case it wouldn’t be a stretch for the person to carry around both of such sparks and never experience any effects at all… which, let’s be honest, might make it a pointless exercise from an RP point of view.
I think the simplest answer to your question, is another question. What is it that you want for it to do for your character?
Shadow isnt void technically speaking. Void is the cosmic force, Shadow is the echo of the Void that naturally occurs on Azeroth and which most of the time is actually used.
Same as the Light is a cosmic force, with holy magic being the echo of it on Azeroth. So no, priests and paladins dont wield the Light as cosmic force. They wield holy magic if we want to be correct.
Light and Void are direct opposites, they react violently if being met directly without both sides being strictly guided (What only exceptional “discipline priests” can do).
There is also a mixture of Light and Void called Twilight. That magic is directly tied to the Old Gods however and might stem from the old gods being void-beings while also being worshipped as gods from their followers, from that coming the light- and void-aspects of that perculiar magic.
With that said:
He will blow up as both shadow and holy magic will directly try to interact with one another without further tempering.
Your human in that example would be exceptionally unstable, especially due to his lack of experience in either holy and shadow. Both magics will seek to influence him in one way or another. A short-lived and explosive case of insanity ensues in worst case.
There are the examples of discipline priests, but there is also a reason why they are called discpline priests. You need exceptional willpower to go for both shadow and holy and have to have perfect balance with them, especially when you want to weave both holy and shadow at the same time. Its as, if not even more, volatile than the arcane is described as. While Arcane is just like a tool and doesnt have a mind of its own, shadow and holy are more closer to living and try to warp you to their side when you just use it. Not to say that both holy and shadow are living, more that they actively influence your mind and heart and warp them a bit when you tap into them. Something which the arcane doesnt do typically.
Thing is, OP, I can see where you might want your character to go:
Them discovering their “natural” aptitude of both shadow and holy magic and learning to utilize both.
I dont know though why you would give your character a start that sounds to me at least like a russian roulette with 6 bullets when you could have your human to be normal and have them join the two obvious recognized orders to study: Church of the Holy Light and Cult of Forgotten Shadows.
There is (or was, I dont know) the Conclave which enables both the study of the holy and the shadow arts.
Sir Zeliek is as much an exception as any other undead Light wielder - that being, they’re rare, but not unique. There’s nothing in the lore that indicates being a Death Knight does anything to prevent using the Light more than any other undead.
Notably Sally Whitemane also still seems to retain use of the Light as a Death Knight. https://www.wowhead.com/champion=839/high-inquisitor-whitemane with her Consecration ability.
I would go by how chron 1 describes the forces interacting in the genesis phase of the universe, which is violently in the places they both tried to occupy (on the edge of the dark pockets that popped up in the light universe).
If you had to think of an analogy for it, think of how in real life (assuming there is only one lightsource) a shadow and light cannot share the same surface. In wow, that doesn’t stop the forces from trying with all of its consequences.
Holy magic/shadow I just see as representatives of the forces they’re tied too, sharing in its traits and therefor would react to eachother the same way light/void does kind of like they’re fractals of those forces (shadowlands lore jumpscare)
The Netherlight Temple and Netherlight crucible show that through very careful balance, the two can come to coexist and coalesce.
But, it’s rare, dangerous… And most lack the talent, know-how or sense to make use of it. Oftentimes practitioners of either art find greater success in keeping the two separate.
While I know the dose makes the poison, I think the idea of separating “shadow” and “Void” as well as “holy” and “Light” to be a bit moot in the lore’s current climate and are mostly a vestige of when things were different
I had a whole conversation splitting hairs about the differences between “Fel” (Chaos evil demon magic) and “Chaos” (Chaos evil demon cosmic force)
