It was horrifically slow, horrifically hard. The sheer amount of effort the two of them were pouring into the fight was terrifying, and yet somehow exhilarating at the same time. The Master used that, drew on the exultation of having something to fight, and having the Doctor fight it with him, and pushed again, harder and harder, mentally straining every nerve and sinew, until finally he felt something shift. Felt the beat of the drums change, faster, rawer. Felt the infuriating things move. Felt them give a little.
With the little concentration he had to spare, he tried to communicate with the Doctor. We're doing it! One big push. One more.
It wasn't that coherent, but he hoped it had got through.