This role can select between three potions to use, a healing potion, a revealing potion, and an attacking potion. Each of the potions has a three day cooldown though. With the Necronomicon the cooldowns for the potions are removed. The Potion Master works like any of the roles that would heal, investigate, or attack would work when using each respective potion.
If a Potion Master decides to heal a Medusa which activated gazing, the Potion Master will be turned to stone, losing an ally by accident.