@ENJAY machines is usually electric-based, but not always, a waterwheel can also be considered a machine.
Although the nickname "murder machine" doesn't sound very good in both english and context, probably that's the closest translation to the original word
@Silwith the reason is obvious, IT'S A TRAP! Emiel also said it too. If you know it's a trap, why would a faithful bodyguard send his/ her master there, even with some proctection? the best choice would be to use a doppelganger who is a fighter/ assassin