A select few number of Stands have been able to metamorphose and evolve, becoming stronger and allowing their user to use the Stand in different forms with new, enhanced, or different powers. Some Stands have natural evolution stages, or "ACT"s, that provide them different appearances and different abilities. Its user may be able to call upon different ACTs at will. Stands may undergo a forced evolution upon being pierced with the Requiem-granting Arrow, and are known as Requiem Stands. Such Stands can maintain those forms for as long as said Arrow is a part of them.