These are the external factors needed to make a spell or ritual work. They fall under five main categories. * The right time - when the moon is full, the summer solstice, an eclipse. * The right place - somewhere mystically significant, such as Stonehenge * The right target - spells that only work on werewolves, or people wearing red. * The right caster - spells that can only be cast by someone genuinely happy, or on the brink of death. * The right condition of negation - spells that only work if there is a way to undo them. Examples of Magic Prerequisite include: