The Cistern of Avooblis - The Adventurers' Academy, #5

The skeleton walkers are loose in the land, Wendahl has gone missing, and the threat of Avooblis breaking free grows stronger every day. As adventurers, Dagdron and Earl set out to face the dangers on a quest to discover the dark past of Mazannanan's clan and the secrets surrounding an ancient cistern. Elloriana and Lita embark on their own adventure, which leads them along the hidden path to uncover Wendahl's mysterious past.
As the adventurers delve deeper and deeper into an understanding of what Mazannanan has in store for the land with Avooblis's power, their quest appears more and more hopeless. But as they come together as rogue, warrior, enchantress, and lady warrior, they realize they just might have a chance to prevent their eyes from being plucked from the sockets and stop evil from spreading across the entire land.