Once you have your ingredients in whatever combination you desire, you can put them together and make your skill check to determine how successful you are.
The roll required is an Intelligence Skill Check, with proficiency if you have proficiency with Alchemist's Tools. The DC which you must meet to succeed is decided by the DM, based on what your materials are and what kind of potion you are trying to make. Each potion has a difficulty level, and success is determined by how difficult the potion is to make, and whether or not you have the appropriate ingredients to complete it.
| Potion Rarity | Alchemy Check DC | In Game Time Required |
| Common | 10 | 1-3 Potions per Day |
| Uncommon | 13 | 1 Potion per Day |
| Rare | 15 | 1-3 Potions per Week |
| Very Rare | 17 | 1 Potion per Week |
| Beyond Very Rare | 20 | 1 Potion per 2 Weeks |
As is displayed in Healing Potion, only two appropriate ingredients are needed to craft a Minor Health Potion, but three are required to make a Greater Health Potion. If you're lucky, you might combine ingredients that fulfill the requirements of multiple potions, and craft some unique potions.
Example: Blue Mountain Flowers has Restore Health at #1 and Fortify Health at #3. Spriggan Wood has Restore Health at #3 and Fortify Health at #4. Barley has Restore Health at #2 and Fortify Health at #1. These three ingredients combine well together, not only to provide a strong Healing Potion but also as a strong Health Fortification Potion. Ultimately, this creates a potion on par with a Superior Healing Potion and a Superior Health Fortification Potion simultaneously, possibly even a Supreme level potion in the end.
Attempted crafting of potions with combination effects will further increase the DC.