Sylvanas
"Spawned from shattered timeways and cloistered within the Ruby Dragonshrine, a maddened fragment of the Forsaken's leader, Sylvanas Windrunner, waits restlessly. Having lost everything and unable to find peace, this tormented echo aches for a chance to unleash her dark fury at anything still living within these barren, time-twisted wastes."
It is far from a stretch to see how Sylvanas might be on the path to this fate with a couple more defeats in her future.
Tyrande
"Once high priestess of Elune and leader of the night elves, this time-twisted fragment of Tyrande Whisperwind now wanders the desolate future of Azeroth. Enveloped by eternal midnight, she is forever separated from the comforting light of Elune and torn by questions about why her goddess did nothing to put an end to such madness."
If we are to take all we've seen at face value the Night Warrior is a champion of Elune. But this is an old god expansion so it's less crazy to think there's some trickery here than to think this follower of the lights greatest power lies in the darkness of the light.
Dissapointment in Elune is a sentiment we've already seen from a few of her priestesses as well.
Give yourselves to the night, Elune will guide you from this mortal prison Doesn't this sound dangerously like choosing darkness for immortal powers? Not unlike what happens to Azshara?
The darkness closes in, my vision is clouded. Mother moon I can no longer see your light your daughter is *alone in the darkness Further hints that the night warrior might not be a work of Elune.
These are the two bosses I faced today but I will include the descriptions for Baine and Jaina for good measure
Baine
"Enraged by his failure to protect the world and, most importantly, the Horde, this time-ravaged shade of Baine Bloodhoof lingers within the ruins of the Obsidian Dragonshrine. Although he's still as powerful as the tauren high chieftain from the present, within this shattered future Azeroth, this guilt-ridden echo is little more than a discordant vessel of unquenchable malice and anger."
Jaina
"The tormented fragment of Jaina Proudmoore has been split and infused within the shattered pieces of her staff. To restore balance to the timeways, this echo must be defeated. However, the devastating magical power possessed by the once-proud ruler of Theramore is hardly lost to her time-havocked spectre. In this future Azeroth, she is only divided, and waiting...."