Concussive Bolt | Magic: The Gathering
Formats Concussive Bolt is Legal in
Official Oracle Text for Concussive Bolt
Metalcraft — If you control three or more artifacts, creatures that player controls can't block this turn.
Official Rulings for Concussive Bolt
6/1/2011 : If the player is an illegal target when Concussive Bolt resolves, the spell will be countered. None of its effects will happen, even if you control three or more artifacts.
6/1/2011 : If you controlled three or more artifacts as Concussive Bolt resolved, the targeted player won't be able to block with any creatures this turn. That is, the set of affected creatures isn't locked in as the spell resolves.