The Shadow of the Avatar 1: Shadows of Doom - 978-0786903009
[Fantasy Roman]

It was the eve of the Time of Troubles. The chaos of spilled blood, lawless strife, monsters unleashed, and avatars roaming Faerûn was still to come. The gods were about to be summoned to a reckoning, and among them was Mystra, goddess of all magic. She knew it was likely she, along with the other gods, was about to be stripped of godhood.

Yet to shatter governance over magic would mean ruin for the world she loved.  So Mystra made certain preparations, looking always for a worthy successor . . . yet until the Ascension of that worthy one, her power must be preserved.

A lone mortal must carry the greatest share of her divine energy, the silver fire, until the mantle of magic could be reclaimed. It was the fate of this mortal to risk being destroyed or driven wild, without warning.

It was Elminster's Doom