The wizard blocked the sectumsempra and whirled back a hex, face a mask of hate, and Draco gritted his teeth as he blocked the hex. The strain of putting weight on his badly wounded leg was pushing Draco past the limits of his endurance, and he stumbled back as he blocked a repulso. Draco snarled with thoughtless fury as the wizard laughed at him, and struck back, growling the spells under his breath; non-verbals spells taking too much energy and concentration, weak as he was.