I know Google occasionally brings this up first when you ask for Asar-Suti. Proper canon information you best get on the amazing French Cheysuli site Les Ombres de'l Imaginaire which has everything you need to know if you read French. You might be wanting Jennifer Roberson's home page if you can't.
Now for the content needed for RPing AS in Milliways:
Asar-Suti - a Dark God Of Awesome Powers from the "Chronicles of the Cheysuli" by Jennifer Roberson:
"Asar-Suti, the Seker, He who made and dwells in darkness, is the Ihlini god. He was originally a Solindish sorcerer who gained enough power to make himself a god and create the underworld. He is generous with his gifts to those who follow him, and ruthless with those who disobey or defy him. No physical description of Asar-Suti is given, but he is incredibly powerful, and he seems to have a very close bond with the Ihlini who serve him, Tynstar, Strahan and Lochiel in particular. It can be assumed that Asar-Suti is ruthless and amoral, and will do anything to prevent the prophecy of the other gods from being fulfilled. The seat of Asar-Suti's power is in Valgaard, in Solinde, the fortress where the Ihlini who serve him live. The Gate is in the bowels of Valgaard, and this is where Tynstar, Strahan and Lochiel went to commune with him and receive their orders."
For the purposes of the bar, Asar-Suti, who has long transcended the flesh and is pure energy, will mostly take the shape of a young human, possibly Ihlini, with dark hair, pale face, and rather pretty. A hint of violet fire remains on his person all the time; he will at least always look as if he were lit by it. Also, he might sometimes change into a white tiger, also made up by violet flames. Sometimes, he is pure fire; but that's not very communicative, now, is it? He can take whatever shape he wants to, but the violet flames will always be there, and any change will have to go through a phase, however brief, of him being mere violet energy.
That info has changed a lot since this was written; Asar-Suti has gone through many changes since he came to the bar. Nowadays, he always has a physical body, but he shifts shape. He rarely uses his god powers at all, instead opting to mostly be the very powerful wizard he used to be before he deified himself. The only supernatural power (if we postulate that magic is natural on the worlds that have it) he uses is going anywhere he wants in the universe, except the past of his own world - where he can't go, because he's already there, as the Seker in his Gate in the cavern underneath Valgaard - thus making sure he wouldn't change the canon.
He is always somehow purple, though, as if he were walking in his own violet spotlight; he can tone it down very much, though, if he is hiding from somebody.
Asar-Suti is from the Cheysuli Chronicles, and is the property of Jennifer Roberson. He appears here solely for the purpose of role-playing in milliways_bar, from which no profit whatsoever is being made. The RPer responsible for him is yakalskovich.