Block/Check/Counter

http://youtu.be/df8FxGvbRWs

This drill is best practiced against an attacker who attacks with slow ponderous punches. I block the punch, check (or hold the arm still) and then I counter attack to his head or body.

This is not the only way or sometimes (even the best way) to defend but it is one way to deal with a slugger.

Without prejudice