"Stop is prohibere." It takes her a moment, because Latin is difficult and new, and this is a stressful situation. But thankfully, Alex is normally good under stress. Unfortunately, there are some things that her Latin hadn't taught her. "I don't know the word for halt, or if there is one." There's a slight pitch to her tone for a moment, and then because she made the word more of a question than a statement, Alex raises voice with more of a command, and she holds out one trembling hand: "Prohibere!"

Unfortunately, whatever the answer to the riddle is, it's definitely not that, and the skeletons keep coming, even when she reaches for Jack.