One use only. A Power Stone is imbued with a powerful magical invocation. When it is activated by a Wizard before, he rolls any dice to cast a spell, the effect is to enhance the efficacy of the spell. Two dice are added to the casting roll (they can be the only two dice used to cast the spell). Note that using a Power Stone will allow a Wizard to use more power dice than he is normally permitted. For example, a second level Wizard may activate a Power Stone and thus use five power dice to cast a spell (3 basic + 2 from the Power Stone). A Power Stone can only be used once - after one use its power is exhausted.

In a similar way to scrolls, Power Stones are not unique items, but they are prepared by a Wizard prior to battle. It is therefore possible for several Wizards to carry Power Stones, and for a Wizard to carry more than one, in addition to one other arcane item. However, only one Power Stone can be used to cast a spell.