Unicorns were deadly, pure equids that bore alabaster coats and single spiralling horns atop their heads. They were favoured beasts of Proteus. During the Chaos Wars they were matched, along with the Scrula, against the Triumvirate's legions of Nevaharr. Later in the war, their defensive magics would be largely what supported the gods' energy dome that was erected to guard against Pazuzu's Inferno Legions. Han-Tolneth eventually came to the gods' rescue with Ashaxei and the other Greater Dragons, but not before the unicorns had all fallen dead, one by one, as their magics were overwhelmed by the demonic assault.
To replace the unicorns, Agatheis's body was reformed into one, and most of His intelligence and power were stripped. He would redeem Himself millennia later, in the Modern Age, by touching His horn to the Hammer of Phaestus, thus awakening Phaestus the Smith from His slumber. This act was deemed worthy of freedom by the Logos, and Agatheis was returned to His original form.