Taught me how to fight against groups and target them anonymously. I made them miserable by sabotaging their most cherished belongings, having my cousin melt down one of their beloved charm bracelet into blobs. I learned how to steal passwords and used it to access their phones and laptops to post their private pictures/emails/messages to the school network. The most effective was staining and slashing their clothes, forcing the school to lock them up in cabinets they could only access during class hours, meaning they could never sneak out on the weekend. It got to the point where one left after she begged her parents to let her come home.
The best thing I ever did was save up peppers from lunch and bake out the capsaicin to grind it into a fine powder and store in tiny pouches of clingwrap. The next time they tried to crowd around me so they could drag me off somewhere to torture, I just cupped one in my hand, slapped one of them in the face and ran. I got a few particles which hurt, but they were screaming and crying before being rushed to the medical campus. After that I visited one who was under observation and threatened to grind it into her eyes and blind her permanently.
After all that, it was just 2 that kept bullying me, but by that point I'd been training with my cousin during visiting hours for weeks, so I knew how to fight dirty. I was so upset I kind of went a little overboard the next time they poked me with a compass. I grabbed her hand, got a hold of her finger, yanked her hair back to drag her down and started bending her middle finger backwards as I spat in her face repeatedly and forced her into the dirt. Once she was down I must have slapped her 20 times as hard as I could, because her cheek split open and I left her a blubbering, bloody mess in the fetal position.