The City Of Dusk by Tara Sim

The Four Realms-Life, Death, Light, and Darkness-all converge on the city of dusk. For each realm there is a god, and for each god there is an heir. But the gods have withdrawn their favor from the once vibrant and thriving city. And without it, all the realms are dying. Unwilling to stand by and watch the destruction, the four heirs-Risha, a necromancer struggling to keep the peace; Angelica, an elementalist with her eyes set on the throne; Taesia, a shadow-wielding rogue with rebellion in her heart; and Nik, a soldier who struggles to see the light- will sacrifice everything to save the city. But their defiance will cost them dearly