The Two Thrones. The Sleeping King Trilogy, #2

The Sleeping King has awakened - and he's everything they feared he would be. Aregor the Uniter has risen to save the world from the Deathless Legion, but his methods are as brutal as the enemy he fights. While he builds an empire on fear and blood, the fellowship that woke him fractures under the weight of their choice. Some join his cause, believing any tyranny is better than eternal undeath. Others form the Free Company, determined to find another way.
As two tyrants wage war across the kingdoms - one commanding the living through terror, the other raising the dead in endless waves - those caught between must make an impossible decision. When the dwarf mountain kingdom of Ironforge falls and ancient secrets lie drowned beneath the Dead Sea, the Free Company races to uncover knowledge that could save everyone... or doom them all. How do you choose between two evils when both claim to be necessary?