As long as you don't use insta win this mod won't get you banned. I have completed around 100 battles with damage multiplier and complete all challenges and still no ban. I just take short breaks between playing next stage. You have to imagine playing the game without mods and see how long it takes to do certain stages. For example the Z power battles first stage you can complete in 5 timer counts with damage multipliers and take 1-2 minute break before starting next battle.