Equestria Daily's Newbie Artist Training Grounds, day 24: Draw a pony's greatest fear / Draw a pony meeting their worst nightmare.

"Such an idyllic plane, full of such blissful dreams, and such wonderful nightmares..."

Ashiok, a Planeswalker that induces nightmares and feeds on the resulting terror. It must have followed Chandra and Jaya to the pony plane, and now Chandra must stand against Ashiok, that her fiery light can prevent his darkness from blotting out the land...

This was the first thing I thought of for today's prompt that wasn't more grimdark horsecrap involving Patch and my ponified mental illness. This is only slightly less awful than any of those ideas.