My players have been asking to improvise specific combat actions, mostly the archer wanting to aim at specific body parts. I haven't been able to find anything in the DMG or the PHB on the subject so I was wondering how I should deal with this.

How (if at all) should an attack roll be modified when targeting a specific body part?

My players have been asking to improvise specific combat actions, mostly the archer wanting to aim at specific body parts. I haven't been able to find anything in the DMG or the PHB on the subject so I was wondering how I should deal with this.

How (if at all) should an attack roll be modified when targeting a specific body part? If there is not RAW on this I am open to playtested house rules per Good Subjective, Bad Subjective.