Aiur fleet... or at least part of the Protoss Grand Fleet , a small part I guess. They are going after the Reapers to wipe them out for good... oh, wrong universe.
Originally this was going to be just another nebula but then the fleet arrived and well... there it is.
Your protoss artwork has always been a special inspiration for me and I've always admired the style you've drawn the race themselves in. Even when other artists have used more detail, the way you do yours has always had far more personality, very unique while still being recognizable as protoss. I hope you'll find the inspiration for some more fanart sometime soon but even if not, you'll always be among my favourites. Keep being awesome.
I love how you descript the fleet appearing while you were painting a nebula. It looks great!