The Old Rock Tower

From publisher blurb:

Decades ago, the wizard Talnabous built this stone tower. For years it was his sanctuary where he could pursue his magical studies in solitude. Slowly his solitude and isolation drove him to greater and greater acts of depravity, including slaying many of the elves in the wood. His final mistake was to summon and enslave a spirit from hell...

Years later, the ruins of the tower now serve as a home to a variety of dangerous creatures both of the wizard's creation and that have arrived from the wilderness. The secrets of the wizard's legacy remain to be discovered in the Old Rock Tower...