Ancient Faulty Blastcore Prototype

This is what seems to be an ancient prototype of what is known as a blastcore, a small explosive that come standard in most militaries. This particular blastcore seems faulty and does not activate upon impact instead someone needs to punch the side of it and it spews out a 20 foot beam of high charged plasma. Anything within the beams range must make a DC 15 Dexterity Saving Throw or take 10d8 lightning damage and be knocked [status]prone[/status], on a success they take half damage and remain standing.

Notes: Damage: Lightning, Combat