There's something that falters in Strange's expression as he thinks. "I'm not sure if I could," he admits. "Harbinger magic...there's something powerful in it. You can't learn an entirely new system of magic in a day and yet these people have. If the spell hit, then they'd be out of luck. But there's a period while I'm casting it that they could put up defenses or just toss something at my head."

Strange obviously doesn't want to admit this. And he's obviously a bit uncomfortable doing so. But Tyki's got to know about the lack of viability for that idea, just in case he starts talking it up or it seriously gets floated as a contender.