One-Shot Sword
Intended to be used in creative worlds if you accidentally spawn mobs with a lot of health (or spawn too many of them) and want to kill them quickly without having to kill every mob in the world with commands, or break your whole house chasing the chickens that broke loose
No more accidentally killing all of your pets because you spawned in 20 dinosaurs, or wanted to check out new mobs you got from mods and didn't think about the consequences
Warning: Keep away from pets that cannot be respawned but can take damage