It seemed like a horrible plan, since the House-elves had all creepily focused as one on the blood pooling on Shane's hand, and since Shane was now trapped in the circle, but Shane was a war veteran and he'd been a seventh-year when William had still been a fourthie, so William did as he was told. He herded the last House-elf into the eerie circle of empty armor, arms linked and shields covering the gaps between legs, and then he turned his attention to a different spell.
"Shane, don't touch any of them," he warned, and then he cast the spell to turn metal red-hot. The suits of armor began to glow, and gradually lost their stern features as they melted together into a misshapen lump of molten iron.
Come on come on come on, he chanted silently as the metal hissed and slowly oozed into the widest gaps, and the House-elves stalked Shane with single-minded purpose. There were still a few holes in their makeshift corral, but he didn't have any more time to lose. Pointing his wand at the ceiling, he called "Planto funis!" and sent a rope spiraling down from the elaborate chandelier overhead, dangling just over Shane's head.