The Midnight Kingdom — Tara Sim

In this “glorious tapestry of magic and murderous gods” (Buzzfeed News) each heir walks a dangerous path, attempting to undo the damage the gods have wrought across the four realms, but they live on borrowed time -- and not all of them will survive.
A cataclysmic battle to save the city of Nexus has left the four noble heirs scattered across the four realms.

Taesia, the shadow-wielding rebel of House Lastrider, and Nikolas, the solider son of House Cyr, have been cast into Noctus, the realm of night. But they are not alone. The dangerous and unpredictable god of light has traveled with them, and he will do anything in his power to destroy Noctus once and for all.

Risha, the peace-loving necromancer of House Vakara, has finally found her way to Mortri, the realm of death. But she still cannot help the wayward spirits trapped in Vaega, nor does she have any idea how to get herself and her friend Jas home. All she knows is that no mortal can survive for long in Mortri. And the creatures that walk the realm of death don't take kindly to the living.

Angelica, the stubborn elementalist of House Mardova, finds herself alone in Vaega. With the other three heirs vanished, it is up to her help keep the city of Nexus from unraveling. But Angelica secretly suffers from a sickness that her goddess left in her veins. And when she is sent on a delicate diplomatic mission, she knows that any sign of weakness will have disastrous repercussions for her family, her city, and her dreams of the throne.

All will encounter old friends and new enemies as they attempt to restore the balance of the world. But as the gods grow stronger, they'll need more than their powers and their wits to survive.