"You needn't be afraid of me. It's my securitrons that are going to kill you."
—Mr. House

Automated Assembly Line

Whenever one or more artifact creatures you control deal combat damage to a player, you get {E} (an energy counter).
Pay {EEE}: Create a tapped 3/3 colorless Robot artifact creature token.

Whenever one or more artifact creatures you control deal combat damage to a player, you get {E} (an energy counter).
Pay {E}{E}{E}: Create a tapped 3/3 colorless Robot artifact creature token.

Fallout

Whenever one or more artifact creatures you control deal combat damage to a player, you get {E}.
Pay {EEE}: Create a tapped 3/3 colorless Robot artifact creature token.