Theo's devices were another rather vital part of this plan. Draco didn't understand half of the math or the science behind their creation or their purpose, but he did know that the pods would, once deployed, release a gas-like substance "similar to carbon monoxide" that would render the Domina members unconscious within ten seconds. It was noiseless, odorless, and invisible, and that's all Draco needed to understand. So long as no alarms were raised once (or if) the effects of the gas were felt, he didn't give a damn about how they were made. He also knew that Theo had exhausted himself in creating them, and that he'd managed to get just two finished before they'd needed to leave. Both were with Weasley, much to Potter's chagrin.