Energetic books were originally a race of shapechanging demons that planned to infiltrate Zathroth's hidden hoard of knowledge to steal enough of it to topple the demon princes and rule on their own. Cunning and knowledgeable they snuck their way through wards and wardens. With trickery and their shapeshifting powers they wormed their way into the heart of secrets. The knowledge they coveted so much was almost at their grasp. Though Zathroth might have seen the effort as admirable, their plot was revealed by his librarians and ultimately thwarted. Before they could finalise their coup, they were cornered, revealed and overpowered. Desperately they made a plea they were doing only Zathroth's work and therefore were not guilty but only zealous, for all they wished for was power through secret knowledge. It is said that the god himself spoke the final verdict on the fiends and forced them into the form of the books they tried to steal. He also bound them to the service of his librarians and to aid them through all eternity. The demons not only retained their original power but indeed were somewhat alleviated by the transformation. So in some way the dark god might have granted them a part of their wish. In the eons since then some aspiring spellwielders managed to summon and bind a few of the energetic books to their will. Most of them are said to be still bound to the holy places of Zathroth, serving as guardians, messengers and even power sources for certain twisted experiments. Little of their ambitious egos remained after all the centuries of servitude. All that's left of them is eagerness to see others suffer too. Their numbers might have declined over the centuries but still there are many of the once proud race around, disgraced, enslaved and with the hatred of centuries to be unleashed on any foolhardy creature they might be sent after.
Energetic Books have 18500 hitpoints. They are immune to energy and holy damage and cannot be paralysed. On the other hand, they are weak against earth damage. These creatures can neither be summoned nor convinced. In addition, they are able to sense invisible creatures.
Energetic Books yield 11900 experience points. They carry book pages, energy balls, glowing runes, platinum coins, silken bookmarks, ultimate health potions, ultimate mana potions and sometimes other items with them.