Vermin keeper

Vermin keepers were individuals who had mastered the control of insects, spiders, scorpions, and worms, whether formerly from the World Above or life long denizens of dark places.

Description
Vermin keepers were skilled in druidic magic, and were somewhat similar to arachnomancers in their mastery of atypical animal companions. Unlike arachnomancers, vermin keepers did not necessarily worship or even enjoy the presence of vermin. Mastering these fearful creatures drove a number of druidic spellcasters to such a discipline.

Abilities
When shapeshifting, vermin keepers assumed the shape of vermin instead of the typical forms druids took. As these druids became more powerful, they could assume more powerful forms of vermin. Vermin keepers chose vermin as their animal companions, instead of druids' typical animal companions. However, these vermin were intelligent. Thus, these companions were able to interact with their keepers as if they were regular animal companions. Very experienced vermin keepers could shift into vermin swarms, which consisted of large groups of tiny vermin who shared a single mind.