Book 5 reveals that Agad was one of the 5 wizards who created Zzyzx and was a pupil of the leading wizard in charge of the project, Morisant. When the demons are about to be released, Agad makes a deal with Celebrant: Lend the aid of the dragons to combat the threat, and Agad would surrender his status as caretaker of Wyrmroost to the Dragon King. Celebrant agreed.
In the end, Agad became the new caretaker of Living Mirage and helps restablish Fablehaven, all the while refining and improvising many fallen preserves and the new demon prison to make it all the more difficult to open so it may never happen again.
During the victory dinner, he counsels with everyone to decide the fate of the Sphinx, who lent his aid in resolving the threat he had worked so long to initiate. After deep counciling, they agree to permit the Sphinx, not only to live, but to become one of the new Eternals needed to keep the prison closed.
It is also revealed that Camarat and Agad are brothers.