If it were a physical movement, it would be quite like side-stepping a javelin or a bullet. The Doctor throws at him, but there's no elegance in it, –he'll have to do so much better than that– no ability to make a concentrated effort because he's harbouring too much there, and he can't control it.

He feels a light wash of agony seep through his own barrier. It sharpens and renews him, and he stops holding back. He pries and pushes until he has command over what his enemy guards, thinks to twist it, change it, even –it would be so difficult and so very worth it– force it to vanish entirely.

I can make it worse. Much worse. Say you're sorry and mean it.