The young god of arcane magic.

R. Archie, The Head Sorcerer, Wizard with the Biggest Hat, The Interloper, Arcane Usurper, Adventurers Boon, Adventures Bane, Master of the Glass Spire City, etc., etc.

A tall man dressed in colorful clothes, his face obscured whenever you try to remember it, an air of magic hangs about him, wearing the largest floppiest wizard hat in whatever room he enters.

Whatever is most convenient or makes him seem more important.

Whatever he wants

the study of arcane arts, an open book, magical phenomenon

Magic, mages, powerful artifacts, non powerful magical trinkets, he's co-opting as much magic as possible

a master of all magic - if someone were to invent a new type tomorrow he would retroactively become a master of it

hubris, anything that blocks magic stops his power, he is tied to a single divine artifact

not properly anchored

simply reading books on magic (Arcanus really wants as much divine power as possible)

trying to make just doing any magic a ritual to him, its not really working, the old god of magic is fighting him on it, the unrestrained research into magic (there are you happy ya stodgy bastards)

doing magic, learning magic, practicing, teaching, experimenting

constantly, he wants everyone to know he exists and is better than the old god of magic

Arcanus was born not of sol saris, the accidental creation of a cult that accidentally believed him into existence via powerful magical artifact, when he became aware, he secreted the artifact away to a place it couldn't be grabbed by others, sol saris, when he himself managed to get there, he found a world to gain more power in, just one problem they already had a god of magic, not a problem, he bought a lordship, the mortals do it, why can't the gods, and ole one eye Tal' zanithal agreed, and so Arcanus began a campaign of attempting to replace the old god of magic

his personal plane is referred to as the Glass Spire City, any one who practices a form of magic can get there but each person does so in a different way
his condition - not properly anchored, is due to him only being able to stay on sol saris as long as his grail does, which is why is pushing so hard to become THE ONE AND ONLY god of magic