Elementals

The Four Great Spirits (四大精霊, Yondai Seirei), also known as the Four Elementals Spirits (四つの), are four powerful spirits under the guardianship of the Four Watcher Families.

Summary
Since ancient times, the Spirit of Water, Undine (Strauss); the Spirit of Wind, Sylphid (Bauer), the Spirit of Fire, Salamander (Hoffman); and the Spirit of Earth, Gnome (Yeager) have been under the guardianship of the Four Watcher Families with their host being chosen by the Great Spirits themselves, as well as being the next head of their respective clans. They are noted to have such immense power that even top-level European Monsters and Beasts could not oppose the Four Watcher Families because of their existence.

Power and Abilities
Each of the spirits has immense power, most of which are based around the elements of their respective Four Elements accessible to their chosen host. Whenever the Spirits form a pact with their chosen host, they can be summoned onto the battlefield and/or enhance the effects of Magic Rituals and Western Magic spells as first shown by Beatrice Strauss.

However, unlike the Five Principal Clans and Sacred Beasts, their hosts can both summon and fuse with their beasts as shown by Weiss Yeager, and Andreas Hoffman and Gertrude Bauer.