A giant gun is a strategic weapon, not a tactical weapon.<br/><br/>Basically, it's for situations when "nuke the site from orbit" is the only acceptable option.<br/><br/>Of course you don't use it to attack the brood itself unless you have a really good plan, but it still comes in handy for taking out monster nests, softening up fortifications, and inscribing occult symbols of doom on the moon.<br/><br/>Besides, Unrealistic?  What's realistic about 500 year old Frankensteins fighting against ancient goddesses and psychic vampires of doom.   I think over the top without godmoding is the appropriate level of discourse here.