Guthix balance potions are used against frozen Vampyre Juvinates. After freezing the Juvinates with the rod of ivandis the potion has three outcomes: The vampyre will be destroyed, the vampyre will become angry (and vulnerable to all attacks) or they will be returned to human form. It is also a medium task from the Morytania Achievement Diary to make a Guthix balance potion while in Morytania.