The only problem with this plan was that the House-elves were getting around their blockades faster than they were setting them up. William animated his suit of armor with a quick slash of his wand and kept two of the House-elves at bay with a broadsword while he levitated a shield to block the third getting close to him.
"Alacritas!" he shouted, and an entire wall of armored knights snapped to attention. He pointed his wand at the prowling House-elves and ordered, "Proficiscor!"