One of the key features of the Witch in my campaign is the ability to create potions. After all, not only is it something people currently associate with them (Eye of newt, etc), it has a long historical tradition. Shakespeare had witches crafting some sort of evil brew at one time, and the most recognizable thing associated with a witch, (Pointy hats not included. Those are, I believe, fairly recent, plus wizards have a pretty good claim to the things if anyone does wear them in a campaign of mine.), with the possible exception of a familiar, is their cauldron. As such, I propose the following rules for potion making by witches:
The witch must know the recipe and have the ingredients. Optionally, there must be a certain number of them, as well, but that's purely optional. For example:
Potion of Cure Light Wounds:
Leshtir-grass (1 lb.)
Kobold Bone Marrow (One armbone worth)
Bugbear Liver (Whole)
Orc Eyeballs (5)
It will take 5 hours to create one.
Potions will fail on a roll of 1-2 on a d6. This reflect the difficulty of getting temperature, etc. exactly correct on a wood fire.