The Book of Azrael - Amber V. Nicole

Two destroyers of worlds meet...

A thousand years earlier, in the deserts of Eoria, Dianna gave her life to save her dying sister. She called for the help of anyone who would like to listen to her, without suspecting that the answer would come from a monster she could not have imagined, even in her worst nightmares. Now, she is ready to do everything Kaden asks of her, including getting her hands on an ancient relic that belonged to the same creatures that chase her.

A king who was believed dead, and disappeared from memory

In the old world, he was called Samkiel. In the new one, it's Liam. However, one of his titles has crossed the ages: he is the destroyer of worlds, a myth in the eyes of his enemies, but a savior as well as a king for those who have sworn loyalty to him. After the war of the gods, he isolated himself, hid from the world. He rejected his crown and his responsibilities, going so far as to leave those who needed him most to take care of the consequences of the fall and death of their home world. Now, after an attack on those dear to him, he finds himself again in the dimension he would have liked to never visit again, and in the crosshairs of an enemy he thought had been imprisoned for an eternity.