To use alchemy, you'll need a Mortar and Pestle (found in Twigroot Forest), and you'll need some combination of the six ingredients available in the game:

Blackmoss	Crystal Flower	Falconskyre
Blooddrop Cap	Etherweed	Mudwort

Then to create a potion (or a bomb), you'll need to have one of your characters equip the Mortar and Pestle, then right click on it, and then select up to three of the ingredients. If you use a valid recipe, then you'll end up with a potion (or bomb).

Having an Alchemist in your party isn't required, but Alchemists will "grow" any ingredients they have in their inventory, making them useful for alchemy, especially for obtaining Crystal Flowers.

Standard Potions
Ingredient(s)	Result	Alchemy Level(s)	Recipe Location
+	Antidote	2-5	Sleet Island
+	Antivenom	2-5	Sleet Island
	Energy Potion	1-3	Twigroot Forest
	Greater Energy Potion	4-5	Twigroot Forest
	Greater Healing Potion	4-5	Twigroot Forest
	Healing Potion	1-3	Twigroot Forest
+	Potion of Bear Form	4-5	Herder's Den
+	Potion of Resurrection	5	Cemetery
+	Rage Potion	4-5	Sleet Island
+	Shield Potion	2-5	Twigroot Tunnels
+ +	Speed Potion	3-5	Pyramid of Umas

Attribute-Boosting Potions
Ingredient(s)	Result	Alchemy Level(s)	Recipe Location
+	Potion of Dexterity	5	Crystal Mine Entrance
+	Potion of Strength	5	Crystal Mine Entrance
+	Potion of Vitality	5	Crystal Mine Entrance
+	Potion of Willpower	5	Crystal Mine Entrance

Bombs
Ingredient(s)	Result	Alchemy Level(s)	Recipe Location
+	Fire Bomb	4-5	Sewers
+	Frost Bomb	4-5	Sewers
+	Lightning Bomb	4-5	Sewers
+	Poison Bomb	4-5	Sewers