In a timeless past, the Triumvirate of Water had a meeting to discuss the rise and influence of the domain of water. During this meeting, the three greater elemental gods agreed upon the creation of an avatar that would embody the three of them in unity. The creation of a pure, untainted being to represent them equally proved to be an arduous task. A great and demanding ritual was required – one that would be ale to leech a part of each of their essences and combine them into the mind, body and soul of an avatar.
To begin the ritual they used an onzolan crystal, through which they would each poured a small portion of their respective essences. Povar was the first to give his essence, infusing the crystal with the power of vapor – the light, delicate and near intangible state of the pure element. E'ci, the Wintry Guardian, contributed the essence of ice – the absolute solidified state of the pure element. Tarew Marr, the leader of the Triumvirate and Lord of Water and Fathom Lord, was the last contributor, infusing the crystal with the power of water – the most abundant state of the true element. With that part the ritual completed, in unison, they each let loose an awesome display of their divine powers. Through the combined might of these deities, The Avatar of Water, Coirnav was forged.
Coirnav came into being as a small marine creature and was at first very weak. The Triumvirate constructed a special domain of its own to grow in and one day rule known as The Reef of Coirnav. In time, Coirnav developed special powers based on the three forms of water – vapor, ice, and liquid – that was his birthright. More time passed and Coirnav grew to his full form, yet still he lay dormant within his domain, waiting for the time that he would be called upon to fully embody the three.
Source: EQ Website (Fabled PoP Lore- Pt 20)