Does Bristlebane Outrider just get stronger and stronger? | tcgmode

So I played against a friend and she had \[\[Bristlebane Outrider\]\] on the field which got us a bit confused. Her take was, that it gets +2/+0 everytime another creature enters her battlefield and, that these +2/+0 stay permanently and stack up. I said, that it only gets the +2/+0 once per tu...