Dred Cat can perform the combo True Veil with Marduk and Soul Eater with Raphael. This can be considered the canon form that Rand evolves into, since he appears in this form at the start of Devil Children: Fire Book, the continuation of Light Version, to help out Jin. However, it is not stated that a Sol Cat has the ability to change forms at will, or if each change in form is permanent.
Devil Children Messiah Riser[]
Rand can evolve into Dred Cat after beating Hecatoncheir. Dred Cat is the first choice given by him.