Artist’s description from DA:

Look’s like I’m drawing ponies again.

Moonlit Waters is now Moonlight Ripple because “Moonlit” sounds like “Moonlet”, which just sounds plain weird. And what kind of name is “Waters”?

I was playing around with the idea of moon phases and a partially ascended alicorn whose power rises and sets with the moon. In the daytime, she’s a normal-looking earth pony priestess in the Temple of the Water Goddess. When the moon rises, she reaches a partially-ascended state. I imagine she would reach her fully ascended form when she does something epic.

Yeah basically, she’s blue Celestia and water/moon-affliated rather than sun.

I’m still not entirely sure what she does.