Naiads and dryads are both forms of sirens. Eir is a young naiad, with her two best friends, Kathryn and Rhia. They all are best friends with others, but they aren't naiads, they're dryads. Their names are Katie, Eliza, Bre, and Isabella. Both naiads and dryads can use magic. Naiads can move water with just a thought, and command sea creatures to fight or defend them when they need them to. Dryads can use their magic to command land creatures to defend them and can bend trees and vines to their will. Dryads can also heal land animals when they are injured or sick. All of this can be done with just a single thought.
The Deadlands, a twisted, obsidian scar on the land, is the result of humans' misuse of Dryad magic, and is home to a host of deadly wraiths and unexplained horrors. Calen is one of very few willing to brave the dangers that lurk there to get at the vast knowledge hidden within. Many mages die there, and new names are added to the List of the Lost almost daily.
The most recent name, Kiriya, sets a lump in Calen's throat. A student of his during his time as an instructor at the Academy, Kiriya strove to emulate Calen in every way, hoping to become just like him. In doing so, she also emulated Calen's bad habit of going spell hunting in the Deadlands alone. Only, unlike Calen, she hasn't come back.
The Dryads, immensely powerful and normally gentle creatures, have ventured out of their forests as they do every few centuries to check on the land and its inhabitants. They have seen the Deadlands, have realized their mistake in giving the gift of magic to humans. Calen is caught between searching for signs of his lost student and surviving the Dryads' wrath as the two factions of Dryads decide whether or not to erase humanity from existence.