Thomas Holland in the Realm of the Ogres: 2 (Thomas Holland Trilogy)

Tom and his friends restored the barrier - but that was a temporary fix. Now they must find a permanent solution the artifact to protect Elfhaven for a thousand years and bring Tom and his mom safely back home to Earth. To find the artifact they are forced to embark on a dangerous quest through the deadly Demon Forest cross the raging Icebain River and solve the riddle of the Cave of Nightmares. On their desperate journey they must climb an active volcano past scalding geysers and deadly giant ice-worms. Standing in their way are a bungling troll and ogre a shape-shifting demon and a demented fairy queen. With gremlins and wizards in hot pursuit only Toms scientific knowledge and the use of light and dark magic can save them. Did I mention dragons?