L. D. Lewis’ 2018 A Ruin of Shadows is a standalone secondary-universe fantasy novella.
General Édo and her Shadow Army — an army of just seven people — have fought for decades to expand the Boorhian Empire. Each of the Shadows brings their own special skill set to the task of annihilating enemies. Ebony-masked Édo, for example, is essentially invulnerable, which is convenient for a professional soldier.
All careers ultimately end.