- Is reform identified as becoming a positive and team player? Or just not being toxic anymore in general?
Just negative behavior. You don't have to fake being positive, just don't be a jerk and you'll be fine and work back into a good account standing.
- Can a few reports completely reset your reform progress? (Even if you aren't punished)
No. Reports do absolutely nothing except flag your match for review. If you didn't do anything wrong there is nothing to worry about from those reports.
- How long does it take for your behavior status to improve?
Supposedly it takes an average of 3 months to drop one punishment tier, but it depends on your behavior; if you aren't even playing to show you reformed, or you are still being a problem, then it'll take longer.
- How will you know if your behavior status has improved?
Currently there is no direct indication of your account behavior standing, as it would only allow people to push the limits of their toxicity. We want to encourage players to actually reform and remain a better person in the community, not be as toxic as possible without being banned.
- Lastly, if your behavior status does improve, will you taken back a tier punishment immediately?
Yes, that's how it works. You drop down one step at a time. However, keep in mind that severe behavior can result in skipping steps, so even if you dropped down a tier you could still be immediately permabanned for some offenses.
You may find additional info on the Instant Feedback System here; https://support.riotgames.com/hc/en-us/articles/207489286-Instant-Feedback-System-FAQ-
