This is a little piece of code which creates a so called frag grenade. It drops down a tnt primed and kills any player inside a configured amount of blocks. It will not destroy blocks either. So enjoy. The time for the tnt to explode is 2 seconds you can just change the tnt.setFuseTicks() to whatever you want. You might want to add some permissions, or use a command storing the person in a arraylist or hashmap.