It allows you to cast one of the following standard spells at a time: In order to use the Borrowed Power spell, you must activate the 'Set Borrowed Power!' wish by claiming-reward to Pauline. This requires enough runes to cast the spell 1,000 times, resulting in 1,000 charges of that spell. You can only use one spell. Casting the spell then requires 3 astral runes and 1 charge.