William Bhuor, the grandfather of Kluster Bhuor, was a fire mage with purple flames that reached rank SS decades ago, near his death. That is what is told, but everybody knew that in fact, he disappeared once he reached that amount of power.
Since he was old, everybody considered him dead after a decade, and another mage from Valzor reached that rank some years before, Farrah Grieme, that dominated the element lightning.
They both were Grand Masters; William Bhuor was the Grand Master from Viridian before the father of Kluster, and Farrah Grieme was the Grand Master from Valzor, with no correlation to Adel.
There was a slights difference at their age, but they both vanished only a week after achieving the rank SS. Many scholars theorized the possible reasons; some thought a higher power killed them, their bodies couldn't support that amount of power, and many things like that.