The Greater Potentia Potion is a buff potion that, when consumed, restores all Potentias to full capacity, but resets current overflow. It applies the Unstable Mysticalitydebuff which, similar to the Mana Sickness debuff, prevents the player from drinking Potentia Potions but increases overflow by 10%.
The buff lasts for five minutes and, like all buffs, can be canceled at any time by right-clicking the icon.