Whenever you fight as a pair with someone you are closely related to / someone you have extensively trained with, you can use one of your Attacks (i.e. not the full Attack Action ! Only 1 Attack, no matter how many your character has due to their level, etc) to forfeit it as a damage-dealing option and use it as a Grapple/Teamwork/Help for your other Tandem partner instead.
Once you choose this, the next melee Attack from your Tandem Fighting Partner, while propped in this way, is made at Advantage and, if successful, inflicts Maximum Damage (including critical hits).
However, every time you attempt this maneuver beyond the first during combat you must pass a CON save DC 15 or take 1 Level of Exhaustion...
Notes: - only one character from any Fighting Tandem needs to have this Feat for it to be effectively an option.
- whatever constitutes the requisites for anyone to become a Tandem Partner is to discuss with your GM.
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