Book 2 of Beats of the Void
Essence is lost in the middle of a war. She can't return until it is over.
Luna is fighting for the fate of an entire solar system. Her Lunar Light continues to lift hopes.
Fluttershy is fighting with a group of ancient knights in a land few know of. She must become one of them to survive.
These three are the last of their world. Their quests will take them to worlds lost, to the darkest corners of the multiverse, and to places they would have never expected in this, Renovare of Hope!
Two Comments from the Sequel I liked-
"Maddening, I love it!"
"True Madness never ends."
An ensuing story in which a Void Dweller has her memory wiped and ends up in Equestria, later rediscovering her powers and madness insues.
Essence and the ponies are back. Sort of. If them being in three different worlds counts.