You know the glowing effect in minecraft 1.9 onwards that puts white color outline (by default) around entities like players, mobs, ect.
I’ve thought what if you create a very similar visual effect to use in transformations.
examples:
ui sign (aka black hair) : when the player is not surrounded by his aura, they are surrounded by blue outline that disappears when his aura appears.
krillin s transformation from DBS Anime 76:(i dont know the name): they are surrounded by outline of the same color as their base form aura