A Cosmic blast is an experience within a sentient being, meaning within a vessel that carries life.
This occurrence happens as the being projects the experience and image from their imagination into the ether of the unmanifest.
The unmanifest is all which has not happened yet, but which contains the potential of everything happening.
Human minds have the capacity, with practice, to create large scale cosmic blasts, way, into the future of epic proportions. The human mind can create immense scenarios, and can materialize it. The being only needs enough focus, and they can create whatever they can possibly imagine.
This cosmic blast is a manifestation of the artist's brain blasting off into space, creating and firing energy into the unmanifest.