Prime Naaru

Prime Naaru are naaru found on Argus replacing Spirit Healers. Xe'ra was referred to by Turalyon as "the prime naaru", by Prophet Velen as "the naaru prime", and as "the naaru prime" again in Chronicle Volume 3. Xe'ra herself says she was "one of the first naaru to be forged during the great ordering of the cosmos."

Quotes
It is not yet your time. I shall aid your journey back to the realm of the living... for a price.
 * Gossip

Speculation
The "elder naaru" from the Illidan novel was likely Xe'ra as it shared her prophecy.