(Author's Note: I've been working on various versions of this Archetype for quite a while now, including the Scientist and the Hacker. This version is about the most successful I've come up with so far.)
Attributes:
The Promethean is someone who discovers and brings (true) information to a culture whose authorities and/or society does not wish this information to become known. Prometheans known to mainstream society are mostly scientists, much to the relief of the Sleepers (who oppose all occult-oriented Avatars of this Archetype). There have been some exceptions, however, such as Aleister Crowley.
The Promethean is not, despite the glorification of Prometheus in some poetry, a symbol of poetic inspiration. (It is quite possible that there is another Archetype for this, BTW.) It is of knowledge that is definitely true, including by the criterion of that acting according to it can be used to accomplish something (the basis both of scientific truth and of magickal truth).
Taboo: It is taboo to the Promethean to conceal knowledge because of its social impact, or to avoid an area of research because its results may be controversial.
Symbols: The most important symbol of the Promethean is, unsurprisingly, fire. The positive side of this symbol is expressed in candles, lit chalices, and lamps (fire that illuminates); the negative side in the burnings of past Prometheans (suspected to be a leading cause of Ascension) and of books. Other symbols include a white lab coat, lab equipment (once telescopes and chemicals, now more likely biological materials like petri dishes), and today the computer and Internet. In the Tarot, the Hanged Man is a symbol of this archetype, among others.
Suspected Avatars in History: Giordano Bruno (thought to have Ascended when he was burned at the stake), Alfred Kinsey, Galileo, and Darwin. Ian Wilmut's announcement of cloning Dolly made him a possibility, but his statements since then opposing the cloning of humans have probably removed any chance he had. Among those publicizing magick, Aleister Crowley is the leading possibility; whether Gardner, founder of modern Wicca, was one is widely debated. Phil Zimmerman, author of PGP (Pretty Good Privacy; an encryption program that the US government considers a "munition") is a leading current candidate. Richard J. Herrnstein, co-author of The Bell Curve (albeit his incorrect conclusion that we know whether racial genetics influence IQ may disqualify him). Whether Socrates was an example is debated among occult scholars aware of this archetype; the ideas that so annoyed the Athenians may not qualify under provable truths, and his honesty when trying admirals for losing a war may have been more of a factor in his death. Some have claimed that Michael Servetus, a physician and scientist burned at the stake by John Calvin, is an example, but his death was because of his Unitarian beliefs, not his scientific discoveries.
51%-70%: At this level, you must select a main skill that you use to gain or (as in Phil Zimmerman's case) use knowledge. If this skill is not already your Obsession skill, you may flip-flop it. If it is, and you fail on the skill, you can roll vs Avatar: Promethean; if this second roll is a success, you can use that roll (or a flip-flopped version of it, if preferred) instead of your original knowledge skill roll.
71%-90%: This channel is the ability to get information out no matter what tries to stop you. By making a roll against this channel, any person in the world who is thinking about a particular area knows the information you want to transmit (similar to All Is Known)... and that you are its discoverer or relator. (It has to be information that was not previously widely known, of course).
91%+: The Avatar at this level becomes able to progress much more rapidly in their main knowledge skill. Experience points are half the normal number to gain new levels in that skill. (If using an alternate experience scheme in which the tens digit is used as the point cost, the Avatar should be able to use the lower of the tens and ones digits as the point cost.)