After telling Devon about how he activated both of his mana paths at once last night, Elena went on to explain how Jax was able to find them.
After finding out that Elena was missing that night, he quickly made his way to the king who told him that she might be at the black market.
Jax had to quickly head over to the black market but before he left Nathaniel gave him something just in case he encountered any problem.
He hurried over to the black market after that to find the aftermath of the fight and after looking around for a while he found something, a blade similar to the ones Devon always had with him but it had a spell mark embedded on its hilt.
He recognized the mark immediately, it was from Elena. He didn't have mana so he had no way of tracking it but he knew someone who could and with her help, he was able to find out just where she was.