Ok, I've been messing with the custom aura's today and made my own.
here's what files you need and what they do
In your C:\Program Files\Gravity\RO folder (or wherever it is located)
Go into your data folder, make a texture folder, then make an effect folder in that.
C:\Program Files\Gravity\RO\data\texture\effect is what you should see. (the last 3 are the most important)
In the effect folder you should have:
pikapika.bmp (the floor symbol that grows and shrinks)
ring_blue.tga (the rotating thing around your character that has height as well)
freezing_circle.bmp (changes the blue sphere's in the aura to this image for non-trans classes)
whitelight.tga [not sure if this works as .bmp as well] (changes the blue sphere's in the aura to this image for trans classes)
freezing_circle.bmp and whitelight.tga both work for me. I know freezing_circle.tga doesn't work at all.
(currently working on how to make a spinning pikapika2.bmp in there)