Traci Thirteen is a powerful sorcerer and trained detective, part of the paranormal detective organization called the Croations.
While at the Tower, Traci had a friendly sparring match with Stephanie (who was along to give Tim moral support when he quit the team) in the Titans work out room. Traci used her staff to block blows and Steph commented that the magically powered girl is pretty good for someone who doesn't really need to rely on hand to hand combat in crimefighting. Traci thanked her, saying she doesn't want to be a one trick pony, and asked Spoiler to stop holding back.
Stephanie promptly complied, and easily sidestepped Traci's staff to kick her in the face. Traci said, "Nice one!" and Steph helped her up, asking if she's good. Traci responded that she is, though both her ego and butt are a little bruised.
Bombshell aka Amy Allen, former traitor and all around grumpy person, came in to challenge the girls to some "real fighting." Traci pointed out they were sparring and Bombshell wasn't likely to play fair, attempting to defend herself and Stephanie from Bombshell's agression. It didn't work, and Amy started insulting Stephanie, but a potential fight was averted when the hyperactive teen hero Misfit teleported in, setting off the alarms.
Traci and Steph appeared to like each other quite a lot and parted on friendly terms, though neither decided to join the team.
All of this happened in Teen Titans #66.
Lean more about Traci here