Ratchet, Hotshot Mechanic

Artifacts you control are Junk in addition to their other types and have "{t}, Sacrifice this artifact: Exile the top card of your library. You may play that card this turn. Activate only as a sorcery."

When you sacrifice one or more Junk arifacts, you get {r}.

If Ratchet is the target of a spell, you may sacrifice three Junk artifacts to counter that spell.