Hollow Heart Albion

is the Noble Phantasm of Melusine. 
A dragon breath unleashed by Melusine after changing to her "original appearance" by means of the third skill.
Having turned back to her "original appearance", Melusine is no longer a being that can be called a fairy and the light that overflows from her majestic heart becomes a wide-area destruction weapon.
That form could be perceived as a rainbow that covers the boundary, or maybe a gate (pattern from a different dimension) to the spirit world that was opened in this world.
After using this, Melusine will not revert to the vessel as a fairy that she wished "to be like" and instead disappear without anyone knowing.
The Albion from the British Lostbelt continued to fly over the "sea of nothingness" and eventually died out, but this also serves as evidence of the fact that, in any sort of human history, it met a tragic death as a "dragon that failed to return to the star".Fate/Grand Order — Melusine Profile, Translated by Master of Chaos
==References==
Category:Noble Phantasms
Category:EX rank Noble Phantasms
Category:Noble Phantasms introduced in Fate/Grand Order
Category:Anti-World Noble Phantasms
Category:Transformation Noble Phantasms
Category:Dragons
Category:Noble Phantasms of the Round Table