Ogre Castle (After the Spell Wars Book 1)

The ferocious Spell Wars have ravaged the island kingdoms of the Plenn Archipelago for more than a century, leaving behind ghostly remnants only wizards of Durril's ability can exorcise. With his apprentice, Arpad Zen, Durril is hired to remove a haunting of spirits from the castle and grounds belonging to Lord Northdell before his nuptials.
The task appears simple. But the legions of the dead refuse to be evicted. Worse, new spirits appear, dangerous ones, ones challenging even Durril's prodigious skill. The master mage and his apprentice find that Lord Northdell has an enemy capable of summoning the worst of the Spell Wars legions--and they are not remnants. They are newly conjured with full and deadly powers.