He's first level yet says he's done this super powerful act and is now carrying around a curse inside of him that forces him to absorb artefacts in order to live? How is this guy even still alive? He's first level? He has to absorb artefacts? Where is he getting them all from that have allowed him to still be alive? Again, he's first level. Can anyone clear up this confusion for me please? I obviously don't know the whole story I am guessing. This is not a complaint, it's an honest and very curious question.
I think the implication is that he was once a very powerful wizard (perhaps even a Chosen of Mystra?) but that the orb, or the magic he needs to expend to restrain the orb, has drained him so badly that he's effectively been reduced to level 1.
EDIT: In the, probably unlikely, event of him having been an actual Chosen of Mystra during the Second Sundering, it is also possible that Mystra's turning from him was not merely a personal rejection but also involved removal of additional powers granted as the result of his status of Chosen. With the end of the Second Sundering, I believe many gods removed powers from their Chosen though I'm not sure if Mystra was one of these. But the timelines would line up I think, as that would have been a handful of years before BG3 takes place. Though if that happened, it would have been pre-orb, so he'd still need to have been powerful enough after that point to at least try to access the Netherese magic.
