Greyhawk: The Age of Worms
So called "The Smartest Man in Town."
He studied magic in the Free City in his youth, and was quite good at not only the art itself, but at the jockeying for position that accompanies wizard guild politics. He was apprentice to Manzorian in Greyhawk, but grew tired of the backstabbing, and retired to Diamond Lake as a sage, not so much for the money but because he was interested in the questions people would ask a sage.
Allustan has been a huge help for the party. The Artificer, Cog, was sent from the Free City to mentor under the sage, to Allustan’s dismay. But the escapades in the Whispering Cairn has piqued his interest, and though he generally frowns on people interrupting him (such as a dancing Kender in a tux and top hat moonwalking down the banister at the early hours of the morning), the Sage is always happy to learn more about the ruins and lore surrounding Diamond Lake.
Also Owlbears, of any age, are no longer permitted to enter his house.