Cosmetic Mutations: The simplest and least mechanically complicated mutation is a cosmetic mutation. A cosmetic mutation has no game effect other than to change a creature’s appearance in some fashion. Cosmetic mutations cost 0 MP.
Minor Mutations: A minor mutation not only changes a creature’s appearance in some fashion but also grants it a beneficial (if minor) special ability or useful feature, such as darkvision or gills. A minor mutation costs 1–3 MP and can usually be offset by a single drawback.
Major Mutations: A major mutation fundamentally changes the genetics and physiology of a particular creature. Moreover, it grants the creature a beneficial special ability or feature it couldn’t otherwise possess, such as telekinesis or the ability to fly. A major mutation costs 4 or more MP and must be offset by one or more drawbacks.
Drawbacks: A creature with minor or major mutations also has drawbacks to offset them. Drawbacks are special disabilities or vulnerabilities that negatively affect a creature. Each drawback has an MP value, and a creature can spend these MP on minor and major mutations to offset the negative effects of the drawback.