LOW-BUDGET DRACULA METAMORPHOSIS BEAM
When you zap the enemy with this person-portable raygun your target will immediately transform into a low-budget Dracula in a poor quality seasonal pop-up store costume complete with pancake makeup and unconvincing fangs.
Once the target has been Dracula-ized you may then splash them with tap water which they will conveniently believe to be holy water. Puffs of magician smoke will be released from gags pre-positioned inside their costume, and they will writhe and howl and generally overact as though being burned by blessed fluids as per popular vampire lore. At some point, they will fall on their back, at which juncture you may drive a stake through their heart.
Once staked, your Dracula-ized target will spurt red corn syrup from their wound, and then crumble to dust in a creative, if not entirely convincing, special effects sequence mostly accomplished through edits but the last bit with the fanged vampire skull rapidly disintegrating into bone dust is somewhat memorable.
If you have completely run out of conventional munitions and bayonets then Low-Budget Dracula Metamorphosis Beam may offer an acceptable solution to your emergent combat needs.
