The druids were known to have a connection with the natural forces and ways of life. They believed in preserving the balance of nature itself. The word for druid in Gaelic means 'wise oak'. In the present day, druid practitioners pertain the arts, vast knowledge and legacy of their supernatural ancestors.
Likewise with Nature, the druids have a connection to the supernatural. Back in the day they were perceived to know how to access and harness the supernatural; it was said they knew how to shapeshift. The magic of druidism is a combination of herbalism, force of will and mysticism.
The fact that mountain ash can be used as a metaphysical ward against supernatural creatures originates from druidism.
Another herbal tool the druids specialize in is mistletoe, which is used both as a poison and a cure. Druids can use mistletoe in their rituals, but it can also be used against them.
An Emissary is a druid advisor to werewolf Packs. The Emissary's job is to give advice, serve as a confidante and keep the werecreatures connected to humanity. Traditionally, only the lead Alpha in the Pack knows who's the emissary for their Pack.
The relationship between the druids and werewolves began in ancient times. Lycaon and his disciples had become the first werewolves. It was said the celtic druids knew how to shapeshift. So Lycaon's kin sought out the druids in the hopes they could make them human again. The druids couldn't reverse the curse, but they did teach Lycaon how to shift back and forth. Ever since then, druids have served as wise counsel for the Wolves ever since.
Deaton, the veterinarian for Beacon Hills is a known healer, alongside an advisor, for canine werecreatures, using his animal clinic as a base for supernatural creatures on many occassions. He served as the emissary to the revered Alpha Talia Hale back in the day, and now serves as one and a mentor for Scott's Pack.
Morrell, a guidance counselor, served as the emissary for the Alpha, Deucalion, even after he began a campaign of bloodshed and terror forming the Alpha Pack. Morrell, however, maintained her obligation to maintaining balance and compensation, by actively working against them, discretely hiring a mercenary to hinder their actions.
On Teen Wolf, druidic practitioners, like Alan Deaton and Morrell, are born human and by no means supernatural themselves. They simply have the knowledge and are trained to harness the supernatural forces, including how to modify the behavior of shapeshifters.
They have the ability to perform magic based on the arcane rules of mysticism and the occult. They are capable of harnessing, then drawing power from a power source such as a nemeton, the full moon or harnessing telluric currents. Blood magic, i.e. blood or human sacrifices are also a potential component for druidic arts.
A prime example of druidic magic is the casting of a mountain ash barrier to ward off or trap supernatural creatures.
Main article: Sacrifice of Scott's Pack
Julia Baccari, a corrupted druid, used her experience and knowledge of the supernatural to give her the opportunity to survive and have her revenge against the Alpha Pack, becoming a serial killer orchestrating human and animal sacrifices to bestow upon herself vast superpowers. In doing so, Julia defied a druid's traditional beliefs in maintaining balance to further her own agenda, becoming a darach.