How do I use riposte and counter-attack?

Question

One of the first talents in the swordsmanship tree is Riposte:

Unlocks the ability to counter an opponent's blows.

I invested a point into it in my first playthrough, but I never really got it to work. I thought it was a passive effect of blocking, but that doesn't seem to be the case. It seems to be an active ability, but I haven't found out how to actually activate it.

How do I use riposte and counter-attack? Does it use up vigor?

Answer 1

From the manual:

You begin the counterattack with your block up (holding the E key) – when an opponent will try to land a blow on you, the icon on his body will turn into a sword icon for a moment, signifying the best opportunity to counterattack. At this point you should press LMB and Geralt will make a dodge and a dynamic riposte.

Yes, it uses up vigor as a normal block action.