In keeping with the “Explore, Report, Cooperate” motto, engaging in non-consensual character-versus-character conflict is prohibited. Players must obtain the consent of other players before taking an action that would intentionally include another Player Character in a damaging effect or other or harmful effect (such as effects that impose negative conditions).
Some examples include casting a harmful spell on another Player Character or an area that includes them, using abilities with an area of effect that would deal damage to another PC, or moving so that another PC is affected by a harmful emanation surrounding your character.
This rule does not apply in situations where a character is not acting of their own free will, such as if they’re being mind-controlled by an NPC and forced to attack a fellow PC.