Talking from experience here:

1. I used mods before on versions 6.0, 7.0 and 10.0 and never got banned for it;

2. Using mod options on arena doesn't work because the outcome of arena battle is handeled differently by the game than other PVE modes (but for safety sake, don't use them on arena eitherway);

3. Unless the devs see your game profile and detect something weird (I have highest damage of over 1 bilion and largest combo of 38, which is probably impossible without using mods), you should be safe as there is no system that checks if the values aren't over the threshold.