I found the backstory for this Eredar-like race off the WoW forums, THIS MAY NOT BE REAL.
"As the thunderous steps of Archimonde's army approached the summit of Mount Hyjal, all hope seemed lost. The camps of Jaina Proudmoore and the Warchief Thrall were overrun, and the forces of Archdruid Malfurian Stormrage were fighting for their life.
Then, the moment feared by all those fighting for the fate of Azeroth arrived. The Night Elf army was overrun, and the great Eredar warlock, destroyer of countless worlds, arrogantly marched to the World Tree. With flames surging in his eyes, he grasped the trunk with one vile claw... and the entire summit was shattered in a burst of brilliant, white light.
When the radiance faded, nothing remained of Archimonde but a charred skeleton, resting in the branches of the fatally-damaged Nordrassil. Malfurion, Jaina, and Thrall emerged from hiding; it was all an elaborate trap designed by Malfurion to take advantage of the demon's arrogance. In his lust for the World Tree's power, he did not notice the gathering flock of wisps take their positions around him and detonate themselves in a torrent of nature's fury.
With their commander gone, the remainder of the Burning Legion's army was cast into disarray. Malfurion and his companions escaped from the summit of Mount Hyjal, and the remaining Night Elves silently reflected upon the sacrifices of their Wisp companions.
Yet, the spirits of the Wisps lived on. Floating invisibly throughout Mount Hyjal and nearby Felwood, they began to slowly intertwine with the demons that had taken up residence there. Almost imperceptively their presence began to twist the forms and minds of the local Satyrs and other foul, demonic creatures.
Now, a handful of these creatures have been transformed in mind and body; they have the thoughts of the Night Elf spirits coarsing through their veins, yet their bodies mutated to take the form of the last creature the Wisps had made contact with -- the Eredar warlock, Archimonde.
Ashamed of their foul appearance, these creatures took into hiding beneath the roots of the shattered World Tree, Nordrassil. Despite their attempts to hide themselves from the outside world, they found themselves under constant seige from the demons who came to view them as abominations.
Now, with their very existance threatened, these Eredar -- demon in form, Night Elf in mind -- have made an impassioned plea to join the Alliance."