A Gaster Blaster is an anti-human weapon developed by Dr. W. D. Gaster to eliminate Humans. Just like regular Magic, the weapon draws power from the SOUL AURA of creatures, concentrating it into a powerful spell, called a Fission Beam, that bypasses physical matter, but shreds through SOUL TRAITs, effectively deconstructing SOULs without damaging the physical environment.

The Gaster Blaster is simply the tool, like a gun, and is only really the medium for the harmful part, being the Fission Beam.