If you are an employee of Riot then I guess I'd suggest you avoid playing in the competitive areas. It seems like a zero sum move: your employer is monitoring you to an inch of your life (which would probably be considered unacceptable in most other workplaces!) and to win you must play in a toxic environment where it is likely you might react badly and thus be targeted by Riot's HR department.

If you must play for your job, I'd suggest doing one of two things: a. Don't play to win, play half heartedly and don't engage, take lots of breaks and report each and every negative encounter to your manager so they can see that it's potentially impacting on your mental health, or b. speak to management about the toxic environment you are seeing and work with them towards studying what the chief causes are then start putting measures into place to prevent it.