[@Eklispe] She can't keep hidden in combat, however she cannot be smelled, seen or heard by any normal means, such as cameras or 'mortals' however. those who process magic like herself will be able to see a small outline of where she is, not completely see her, but see her enough to know she is there, and if somebody has magic to see her with, they can use that. 

The probability can affect herself and partly others except magic users unless she puts a lot of effort into it which is draining on her. The probability itself is things like, increased chance somebody might fall on a rock. Increased chance somebody will take the alleyway home instead of taking the long and safer way home. Increased chance that somebody might make a mistake that allows her to get close, etc.

And with the Time Pause, he cannot physically kill anyone, but she can use it to set traps, or get close enough to get a chance to kill them. She can also use it to run away if needed to.