PokeBall
http://4.bp.blogspot.com/_DmSesYZLnk4/SuTuY01KpzI/AAAAAAAACiU/X8vgkrf4u0E/s320/pokeball.jpg
Yes, this is also one of the most terrifying out there. This sphere has the ability to somehow change from the size of a marble to a baseball in less than a second. The user can carry up to six with them at a time and they can be easily recharged/stored through some sort of 'Center,' but that's not the worst part. Defying all laws of time and space they have the ability to contain monsters up to 15X times the size of the average human being; all with differentiating powers/abilities/attacks of grass, water, fire, ghost, ice, psychic, dark, electric, rock, flying, steel, normal(wha-?), fossil, and ancient. Plus,you can't kill them, they will just FAINT.
Basically this little sphere of terror allows the holder to carry around a horde of frightfully strong monsters that can conveniently now fit in the user's pocket. Yet the horror not only lies in these 'pocket monsters,' but the users themselves. They are never satisfied. They even make it their life's goal to "catch'em all." God help us all.