The Persephone Effect (Gunmetal Olympus) by Maria Ying

Zeus has been struck down, and Elysium stands on the cusp of destruction. In this tumult, Persephone is wounded but not yet defeated. A presence grows within her that should not be. She has a chance at the goal she’s strived toward all along: godhood itself. But just as likely, she could lose everything. Now she must adapt—or drown. Hades, head heavy with her sister's crown, labors to bring the gods to order and keep them united as a killer haunts the city, capable of dispatching mortals and gods alike. Twin gods Artemis and Apollo grow increasingly erratic, hinting at a scheme that may no longer align them with the survival of Elysium. In the battle for Olympus, the gods must unearth the secrets left behind by their makers—who may not, after all, be entirely gone...