Hmm...I just came up with another crazy idea, that is almost certainly false. What if Auric Ulvin is actually Kyorlin, possessed by the spirit of Mulcarn. I imagine the spirit of the dead god may have fled to the closest host, his slayer. Alternately, Kyorlin may have tried to harness his power, and bee overcome by the will that came with it. The struggle within him was so intense that it cleared his (conscious) memory and created the tabula rasca personality of Auric to protect itself. Or, he could have cleared his mind on purpose to protect his knowledge from Mulcarn, and slow his return to power. He probably hid the Godslayer from himself before he was overcome by Mulcarn, perhaps taking into the Shadowed Vale. I wonder if he thought the Heartstone would help him rid himself of Mulcarn, but was delayed too long and had lost control of his body before he could use it. Having the power of Kyorlin but not his knowledge would explain his uncontrolled affinity for magic. Of course, I believe that Ulvin is specifically stated as being much younger during this episode, so this is almost certainly not the case.