Naaru

The Naaru are inter-dimensional beings with a deep affinity for the Light. Intent on stopping the evil of the Burning Legion, the Naaru assisted the Draenei in their time of need against the Legion and work to form an opposing Army that may defeat the Burning Legion.

Naaru appear to be compose of numerous crystals suspended in the air, floating around a central "heart". One could note that the presence of a Naaru seems to emanate a sort of song, a soothing tone for all near the entity. However, this tone has also been capable of change, as shown with M'uru, in which the tone could become more melancholic, presumably due to the Naaru's darkened state.

The Naaru's darkened state can be caused through managing to damage the Naaru. When this occurs, the Naaru becomes darkened and releases Void energies. While the Naaru may still hold altruistic intentions, a weakened Naaru becomes easy to exploit, in order to create Void minions and use Void energies.

Eventually, a darkened state may produce a Void God, but this has only occurred when the light was forcibly drained from a Naaru, meaning this may not occur naturally. In the event that a Void God dies, the creature may leave behind a "spark", as shown with M'uru. It is questionable as to whether or not the spark itself can regenerate into a Naaru once again.

Songs of the Naaru
The songs of the Naaru can vary, depending on the state of the Naaru. A living and healthy Naaru, such as A'dal, will mostly like have a pleasant, soothing song. A darkened Naaru (the below video) will likely have a melancholic, depressing song.