The Book of Azrael

For a thousand years, the Etherworld has known peace, until now. Many centuries ago, desperate to save her dying sister, Dianna gave up her life and made a deal with Kaden, a monster far worse than any nightmare. Locked in servitude, she must now hunt down an ancient relic held by her most dangerous enemy. Once known as Samkiel, now living humbly as Liam, only one title remains true throughout time - he is the World Ender, a myth to his enemies, a saviour to those loyal to him. After the Gods War and the death of his homeworld, he locked himself away, denying his crown and deserting those who needed him most. But now an attack on all he holds dear sends him back to the one realm he never wished to visit again, and into the sights of an enemy he thought imprisoned eons ago. With every realm at stake, Samkiel and Dianna, enemies older than time, must put aside their differences and work together before all is lost.