So I was looking at the new genetics chart, and whilst Cairngorm has joined Ashen in the Black Light Solid Special breeding since originally posting this suggestion, it looks more like a countershaded base than a solid. Therefore, I am suggesting a new solid base to further encourage breeding in the Black Light Solid Group, because since lilac left the group, it has been lacking its own weird desirable base.


And without lines:


It is a very light shade of blue to pair with Ashen in the Black Light Solid Special Group. Maybe it could be a hard to pass base similar to lilac? Or, following on from the recent news post as of 15th of September (2017) maybe it could be a combo base resulting from one of the December bases and a light base (e.g Buttermilk, Buff, Sunshine and Ashen)?

Edit: Due to the next December event base confirmed to be called glacial, I've changed the name of the base to Frost. Feel free to suggest other options :3

Edit 2: I now think that this would be a base best suited to being a rare base - a light blue version of ebony.

Other base names
Periwinkle
Lapis
Marian
Forget Me Not
Thyme