The principle
Reflect their behaviour back at people and they are forced to see themselves. Mirroring teaches lessons no lecture can — and infuriates opponents who recognise the move only in retrospect.
The application
Copy a competitor's tactic with a small twist, and you neutralise their advantage while making them feel imitated. Used carefully, this is judo. Used carelessly, it is mockery.
The defensive tell — how to spot it being run on you
When a rival starts producing work, language, or moves that feel uncannily like yours, do not assume coincidence. The mirroring is sometimes flattery and sometimes intelligence-gathering with attribution. Move your work somewhere they cannot see the draft.