Demon Rising: Demon's Fire Book 3 - Dream Walker Chronicles, #6

Erik Eleodum is known as Wolf's Bane, Troll Hammer, and Dragon Slayer. Now, he must become a Demon Killer. As Yebritoch, the Lord of Chaos, regains a foothold in the world and threatens to break free of his prison in the Abyss, Erik must stop him before he destroys the world and tries to rebuild it. Through his alliance with the Lord of the East, the demon Yebritoch has found a pathway from the Abyss back to the world.
If they can free the greatest of Yebritoch's Chaos Beasts, his transformation will be complete and there will be no stopping him from raining chaos upon everything. As this ancient evil devises a plan to destroy and rebuild the world, Erik has developed new allies as well as reunited with old allies and journeys into uncharted lands to find the last missing piece of the Dragon Scroll - the Dragon Crown - and a weapon that will help stop both Yebritoch and the Lord of the East.
But his confidence is shaken and he questions whether or not he can actually stop the Lord of Chaos. Will Erik have the strength and heart to make the sacrifices needed to stop the Demon of Chaos, or will the world as he knows it end?