When you want to attack an enemy, and you're using the mouse, you left click on them.
In Polymind, if your detection level isn't 100.0%, this makes you move instead which can be somewhat annoying.
There is however one scenario where it's really annoying :
When i've just taken control of a new host after leaving one in the middle of a fight (where i was just left-clicking to attack), making my detection rate lower by a little bit.
Because i've just been using left click to attack several times, i do it again, making me move instead, making my detection rate reach 100.0%, meaning the unaware get free shots on me.
This happens every single time i get a new host during a fight, and the last time it happened, it might have been the difference between life and death¹ (I died, placing me 11th on the score leaderboards).
¹I had made mistakes that brought me into this dangerous state, but still.