Well. That was disappointing. And Severus sighed as well, frowning slightly. Not even a hint of silver mist, but he'd hardly expected Magius to get it on his very first try, either. He had no doubts regarding the man's skill, after all, but this was an entirely new form of magic to him, even if the processes appeared to be similar, at first blush.
"All right," he said with a nod. "Do you feel up to trying it again?" Because failed attempts at a Patronus could be draining, but he also had no doubts regarding Magius's power, if ... whatever he'd cast that had taken out Severus's Disillusionment Charm was any indication.
He took a deep breath and held it in, again willing this second attempt to work. Though he didn't think he needed to remind Magius of the incantation, Expecto Patronum kept running through his head, as if on an endless loop. As well as their previous encounters and how he had taken to the fellow almost immediately. In fact, Severus was concentrating so hard on how much he wanted this to work that he never even noticed the silver wisps emanating from the tip of his own wand.