The Armor of Light by Melissa Scott
Approx. 171,130 words.
Published on October 18, 2013 by
The heavy summer air of 1593 is full of portents for Elizabeth, England's Queen, and James VI, King of Scotland. A coven of witches secretly controlled by the Wizard Earl of Bothwell has summoned a storm to sink the ship that bears James' bride to Scotland. Though the ship made port, the success of their summoning has emboldened them; the coven is now launching wizardly attacks on the King.