Players can abuse a glitch for completely invincibility in spars (and maybe elsewhere). Someone just queued vs. me and was totally unhittable, and stopped to let me swing through him 100 times and said this is how he believes it happened:
I've seen a ton of people abusing this lately. I didn't test it and don't know if that's how to reproduce it, but it needs to be fixed. Some people seem to have it happen accidentally, but I had someone use this against me in the middle of an 89 streak and say something ******ed like, "AHAHAHA, dis is what PCs deserve!" so it's easy to abuse.
I've also reported this another 20 times before, but the /350 spar rating reset glitch still needs to be fixed. People have been abusing this for months (namely Comyt, if I've got to be honest) to get high positions on the leaderboard. All an iDevice player needs to do is log on to the same account from two devices at once and their rating persists while their rating deviation is reset to 350. It's dumb and needs to be fixed. Or, you can just switch to the leaderboard system that I proposed in another thread, that doesn't rely on rating at all.