Performed various testing to evaluate multiple theories that I have had.
First test was on an account with 2*s, 3*s, and 4*s. No 5/50 or 4/40 4*s, only a couple 3/30s. maxed 2*s, and 2/4 of all 3*s were maxed. I ran through homecoming quest, heroic and master difficulties, within a day's period and received instant ban. Banned permanently. No prior ban on the account. Built this account over the course of 1 month.
Second test was on an account with 3*s, 3/4s of all champions maxed out, 4*s, 3/30s and 1 4/40, with a few 2*s laying around. Also possessed 1 5* 1/25. Ran through previous monthly quest, Secret Empire Forever, last month. Completed heroic and master difficulties over a period of several days. No prior bans on account. Been building this account for several months. Started Homecoming quest today. Ran through heroic, and than banned half way through master difficulty. Received email of permanent ban.
Third test was on an account with 3*s 3/4s of all champs maxed, several 5/50 4*s along with 4/40s and 3/30s, and 8 5*s, 2 of whom are duped 2 times. Been building this account for 5 months. Have ran through LoL and RoL multiple times with sensible teams. Have not received ban. Possesses Legend title from last month's SEF quest. Recently completed homecoming quest, both heroic and master difficulty under 4 hours and 30 minutes to achieve time attack legend tag again. Everything has been running smoothly on this account.
The theories, as you can figure out on your own, are true for some and not for others. Approaching each quest, LoL and RoL, and arena run, with some sensibility will help you avoid major risks.
I have been using using mods on my main account for months now. No ban. Don't let common sense elude you by heading in aw or even aq with 2*s and 3*s or even low tier 4*s. Be smart in how you play.
#ViVaLaDiDA