Limits of Power: Paladin's Legacy: Book Four

MAGIC WILL NOT BE ENOUGH

The Lady of the elves has been slain and King Kieri injured by the iynisin, a corrupted race of elves whose poisonous touch means grisly death for all who stand in their way. As the Lady's elves retreat to bury their dead, strange discoveries are made in the palace, revealing old secrets about the ancient alliance between humankind and elves.
Meanwhile, in the kingdom of Tsaia, young ­­­Prince Camwyn begins to exhibit dangerous signs of magery. Discovery of magical blood so close to the king will put his brother's rule in jeopardy, but he has nowhere to turn when even his own family might put him to death for treason.