Children of fire - Drew Karpyshyn

When Daemron, the human champion of the Gods, betrayed the Immortals and sided with Chaos, he started what was to become a long and bloody war.

The Gods sacrificed themselves to contain him, but Daemron had one last means of escape...

Now, four children must bear the consequences. Born apart with very different lives, Keegan, Scythe, Cassandra and Vaaler share the taint of Chaos magic. They are the Children of Fire - warrior, wizard, prophet and king - and they are our only hope of restoring the balance of this godless world.

... else he will return. And we will all be doomed.