The Iron Thane — Jason Henderson

A historical fantasy novel that imagines the adventures of one of Shakespeare's most famous characters after he kills Macbeth.
 
Lay on, Macduff! And damned be he who first cries Hold, Enough!

Macbeth was just the beginning. Amid the smoke and chaos following the destruction of Scotland's mad king, the Prince of Dark Elves decides the time is ripe to unleash an assault on all of humanity. And he will begin by doing what he does best: stealing the souls of children to build his army. The Erl-King's victory is not inevitable; he can be stopped -- but those who have the power choose not to.

The three immortal Sisters worry about Fate. Oberon, king of the lightning-fast little people, will not risk his legions. The Erl-King's own son, fully as powerful as his father, would fight, but his mother will not let him -- and he is only five years old.

In all the world there is one who might bind together these disparate forces and lead them in battle against darkness: Macduff, Thane of Fife, a mortal who thinks he has outlived a destiny that has only begun.