Warcraft: War of the Ancients Vol. 2 The Demon Soul (novel)

The night elf defenders, led by the young druid, Malfurion Stormrage, and the wizard, Krasus, fight a desperate battle to hold back the Legion's terrible onslaught. Though only embers of hope remain, an ancient power has risen to aid the world in its darkest hour. The dragons -- led by the powerful Aspect, Neltharion -- have forged a weapon of incalculable power: the Dragon Soul, an artifact capable of driving the Legion from the world forever. But its use may cost far more than any could have foreseen.