Fantasy: Alchemy

Alchemy uses Physik (the Science equivalent) as its base skill, and covers the creation of potions, elixirs, philters, ointments, powders, and the like.

The default difficulty is Mediocre (+0). Shifts obtained on your Physik roll can be spent on:

• Power: The effect of the concoction -- what it does. With rare exception, this will be beneficial (harmful formulations are better classified as poisons). Pick a skill, such as Alertness, Endurance, Resolve, Might, or whatever is most appropriate to the effect you want to achieve. For example, if it's a potion of strength you're after, pick Might. Each shift spent on Power increases the quality of this skill by +1.
  
• Duration: How long the effect lasts, starting at a minute. Each shift spent on Duration increases the length of the effect by one step on the Time Chart.
• Aspects: Shifts can be spent to add aspects to the imbiber, as well, to reflect grey-area stuff. If your potion turns someone into a bestial humanoid, reflect that by spending a shift on "Bestial Humanoid." A potion that has a visible effect on the imbiber -- for example, if he sprouts wings or is covered in a chitinous armored shell -- must have an aspect.
  

Alchemy requires a default of 15 minutes to create a potion. For every shift spent on Power or Duration, increase the time required by one step on the Time Chart. Unspent shifts reduce the time required by an equal amount -- one step per unspent shift.

Apply the potion's Power to the user's relevant skill as a bonus for the duration of the effect. Optionally, an entire category of skills (physical, mental, or social) could be affected at twice the cost -- two shifts/+1.

Example:
Augustus, eager to get the better of an upcoming business transaction, pays an alchemist to create a potion that will make him more persuasive for a while -- a Rapport effect. The alchemist has Good (+3) Physik, and rolls a +2, for a total effort of Superb (+5). He spends two shifts on Duration, to make the effect last for 15 minutes, leaving him with three shifts to spend on Power. It'll take the alchemist all day, but his customer isn't in a hurry. When he's done, Augustus will be able to receive a +3 bonus to his Rapport for 15 minutes. Hopefully it's long enough.

There's one other factor: money. But that's a pretty individual matter. For us, until we figure out how much things cost, or what money's even called in one place or another, it'll be tough to pin that one down.

What about potions that have effects entirely outside the skill system? Like a potion that gives you the power of flight, or one that turns you into a monster?

I think the easiest way to handle the former is to, well, fudge it. Make up a new skill to cover the new capability, like Flying. Nobody has flying, except flying things. You don't even have it at Mediocre (+0). But drinking a potion that gives it to you also gives you the power to use it, so if you spend a few shifts on Power to give the imbiber the Flying skill, now they can fly. Just to keep things from getting totally out of hand, though, giving someone a skill that isn't normally available costs two shifts per point of bonus. Average (+1) Flying is good enough to fly, but if you want to stand a good chance of catching or outrunning another flying thing you'll want to bump that up -- which makes potions of flight expensive, difficult, and time-consuming to make. And they should be, at least in my game.

As for monster-turning-into, that's a little easier. Let's say your potion turns the imbiber into a werewolf-like thing with supernatural strength, big sharp claws, and a canine sense of smell and hearing. Spend Power shifts on multiple skills -- Might, Melee, and Alertness -- and another shift on Aspect: Big Werewolf-Like Thing. Again, it'll be costly, hard, and take a while, but look what you're getting in the bargain!