The rejuvenation formula is a spell that can change one's age though it can also switch the ages of two people if they both activate the formula at the same time with an explosion. Little is known of the ingredients or actual reversion of this spell. It is a vaguely detailed spell from one of Gargamel's books in "Gargamel's Second Childhood," with which he and Scruple switched ages by pulling apart a twisted cloth containing the necessary ingredients. The only way to reverse the spell was by recreating the process by which it first occurs. However, Papa Smurf tricked both Gargamel and Scruple by having double the amount of the formula's mixed ingredients put into the cloth, so that when it was pulled and the formula exploded, Gargamel became a shriveled elderly man unable to go after the S