Conceptual entity

A conceptual entity was a being or weapon (sometimes both) engineered to be only a concept, with no actual physical substance from existing only as an idea.

The Celestial Intervention Agency became the conceptual entities called the Celestis after turning themselves into completely conceptual beings to avoid being destroyed by the War in Heaven, removing themselves from history so that while they never physically existed, the "idea" of them survived. The Celestis later became experts in the creation of other conceptual entities, such as anarchitects, gargoyles and shifts, weaponizing them to use during the War in Heaven. (PROSE: The Book of the War)