Nar'thalas Mages

[Amadis-draka (Amadis)]

@Drahliana-earthen-ring

The only thing Blizzard seem to had intended for the Night Warrior was to open up the Darkshore Warfront.

Which is annoying that they would overlook their own lore:

@Verlius-kiljaeden

“ In contrast to the previous times that they had met, the novice priestess of Elune-the Mother Moon-wore an outfit more befitting the way of war than the peace of the temple…
To Malfurion, she looked more like the priestess of a war god and evidently Tyrande could read such in his expression. With a bit of defensiveness, she admonished him, "You may excel at your new calling, Malfurion, but you seem to have forgotten the elements of Mother Moon! Do you not recall her aspect as the Night Warrior, she who takes the courageous dead from the field and sets them riding across the evening sky as stars for their reward? ”
Knaak/WotA

This is also stated in game in an Archeology item:

Necklace with Elune Pendant


Elune is the primary goddess of the night elves. She is associated with the larger of the two moons, the White Lady. While she is a goddess of peace, she is not a pacifist. One of her aspects is the Night Warrior, who takes the valiant among the dead and sets them riding across the sky as stars.

This is likely what we saw with Ysera in Val’sharah.