I noticed a striking resemblance between the glittering navy blue magics that engulf the Alliance champion/the fallen Horde and the artwork for Ardenweald while doing the Night Warrior chain again recently. Assuming the artwork is consistent, it really looks like whatever power Elune is bestowing upon the Army of the Black Moon is either from, or coincidentally also within the Ardenweald.
You can see it flowing out of their trees.
And at the feet of these corpses.
As their glittery navy blue brand of energy -- if there was any truth to this:
And as Tyrande's intended destination in Shadowlands. Presumably the answer she's looking for is to why Elune abandoned her children."
It also might be worth noting that on the same questline, the Forsaken Val'kyr Brynja uses the purple chain magic on the Alliance champion that Sylvanas used on Bolvar in the new cinematic. Shandris also notes that Maiev has become more powerful after dispatching some plague troopers, which the warden attributes to vengeance -- but I couldn't find any Revendreth magicks coming off of her haha!