Death knights and shadow magic.

We need a discussion on this, quite simply. To summarise: yesterday, Morbid Faith attempted to seize a prisoner of TTF from Theramore and during the ensuing battle, one of TTF's death knights claimed to be immune to "negative energy". By which he meant "all shadow spells". I hope you can all see why this leaves us in a bit of a pickle. Almost all of MF rely heavily or exclusively on shadow magic.

Now what I'm hearing from TTF is, "It's fine in the lore, shut up. By the way, we're even, because of Alrick."
Why? We kicked Alrick for powergaming and you're going to hang on to this death knight guy for as long as you see fit. What's more, two wrongs don't make a right. I clear up problems when they occur, you sweep them under the carpet? I took action in response to TTF's complaints, but mine aren't considered? Great.

Lastly, let's come to the supposed lore on this. What is this "negative energy" in Warcraft lore? I've seen it used in the heavily D&D-influenced tabletop RPG, but only in reference to RPG game mechanics and nowhere else in the lore. This is what bugs me: if I used something that existed mainly in WoW game mechanics to justify an overpowered RP ability, I'd be flamed. The RPG books can be a good source of lore, but we need to distinguish what's simply making the game work and what's actually the case in the Warcraft universe in which we roleplay.

I am happy to compromise on the matter. I am happy to accept the individual in question being highly resistant to shadow magic, maybe even healed by Kassina's death coils. But I have yet to see anything in lore specific to Warcraft that states undead are fully immune to shadow magic. Your argument appears to hinge on the use of D&D game mechanics as Warcraft lore and I'd like you guys to clarify if that is the case. If not, where is this coming from and what is this mysterious "negative energy" in relation to our magic? That, to me, sounds like a quite D&D-specific term being used in a WoW context.

I will not tolerate being dismissed out of hand and I will not tolerate my arguments being brushed aside. I can and will hand out IP bans to anyone who cannot keep a civil tongue in their heads. We can only arrive at a satisfactory solution by discussing this properly. I hope that's clear.