Mysteries of the Phaerimm

This aged, leather book sheds light on the phaerimm—telepathic, funnel-shaped monsters of malevolent intellect that lurk in the Underdark—and includes disturbing sketches of them. A few sections of information are available in this tomes:
 Phaerimms were conical in shape with ovoid heads. They had barbed teeth and a venomous hollow barb on the end of their tails. Phaerimms had four arms. Their spiked, slug-shaped bodies were a greenish color covered by rough, scaly, and leathery hides. The Phaerimm were believed to be wholly evil monsters, their alien thinking utterly inscrutable to the few mages who sought them out for research purposes. Though their penchant for cruelty has the potential to make them predictable, this hardly matters in comparison to their horrifying natural abilities. Phaerimms were incredibly powerful spell-casters. Not only were they capable of casting far more spells than most Netheres mages, they had developed their own unique spells, which could only be cast by phaerimms. They specialized in mind-controlling spells, and casted such spells naturally without need for components. The book contains a dedication to those among the first research team to encounter such monsters, most having died in the process, and cautions the reader on the danger such creatures pose to a heavily magic reliant society.