COC #18 falls into to a category I call Monster Chase. It’s a close relative of Monster Mash (discussed yesterday) except that the monster(s) is actively chasing a particular person or group (rather than just causing general mayhem).
COC #18 would probably not make the cut (as it is fairly generic) but for a few details. The name "Monstrom" shows so little creativity that it actually works in this cover's favor. You just know that they cranked this puppy out at the last possible moment. At a minimum, somebody would come up with "Bog Monster" or something really ridiculous like "Swamp Thing." Of course, for our British friends, "bog" is slang for "toilet," so having a "beast from the bog" might be significantly scarier. Finally, it must be noted that the shotgun blasts do seem to have an effect: they make Monstrom's mouth water. Perhaps all he really wants is more ammo and not the girl.
Here's your scream: