"During your turn, you may sacrifice 2 wounds to make 1 additional Magic attack. You may do this up to 2 times per turn. Losing these wounds cannot be prevented by any means".

Is this mean that If I run, I cannot use this capacity? Additional mean that I have to make an attack before using it?

There is already a thread about this 2 threads down (meaning it was second from the top when you posted this question). Your answer is in it.

Link for posterity.