So, one of my players wants to play an Alchemist- not a sorcerer. Although she will likely dabble in sorcery (learning the Art of forging Orihalcum is certainly one of her goals), she's more interested in the passing references to Alchemy, and to Opera as the Alchemical art.
However, traditional Alchemy as the Great Work doesn't make as much sense in Ven culture- since it was a metaphor for perfecting yourself and yourself. And, well. The whole 'Ven don't have souls' thing.
Mechanically, we're treating Alchemy as a kind of cross between creating Art and sorcerous Rituals. Learning an Alchemical formula will take a Season Action and a unit of Herbs- but actually making it will more closely resembling creating narcotics.
Anyways: In her backstory, the Alchemist used a kind of Greek Fire, an oily substance that could not be easily extinguished, to drive away another Baron who thought he could take her lands. This is my proposed mechanics for the stuff:
Tzul: Spiced Firey Wine (Requires Wine and Herbs)
An Alchemical creation, Tzul resembles a thin, pale green-blue liquid. It is always kept carefully bottled. It's suprisingly viscious, clinging to the inner edges of the bottle- or quite tenaciously to any skin it comes in contact with. A counteragent, itself made of Tzul, will dissolve the Spiced Firey Wine as well as render it innert.
Normally, if someone is on fire, the fire can be extinguished by risking a number of Wagers equal to the rank of the fire . However, if the victim is doused in Tzul first, the fire becomes almost a living thing, tenacious as hell. It rolls a number of dice to resist being extinguished equal to it's rank, and may Tag any water thrown on the victim as a Free Aspect for two additional dice. The Tzul's Wagers reduce the extinguishers Wagers.
The Tzul burns away as the victim is consumed, loosing one Rank per beat.
A single unit of Tzul is enough to throughly douse 3 individuals, or set aflame a good sized ship or building.
 A proposed House Rule, to clarify putting someone or something out.