It doesn't "ban you instantly"
You'll get banned if you prestige while using the following mods (because they are passed to the game server on prestige)
- All item bonuses active (if used when you have almost no actual sets)
- Hero Weapons / Scrolls boosted up to 300
- Passive Skill upgrade
You'll also get banned if you pass your "estimated max level" by more than a certain amount (i.e. if you use the Gold Increase mod to go straight to level 5000 from 0 on your first prestige)
You will also get banned from being reported by multiple players when they see you at stage 150k with 8 tournaments played and 200 pets (don't be greedy).
If you're not greedy and play it slowly, you can safely use the mod without any issues. Remember, this game is not designed to be "quick win" and you'll get caught if you think it is.