Obstruct

You sense incoming danger and are able to quickly avoid it. When you are the recipient of the damage and/or effects of a move, you may automatically avoid the damage/effects on the first instance of this reaction. On future instances of this move in the same combat, you must roll higher than a 15 on a d20 roll for the reaction to be successful. This reaction may not be used to guard against the damage/effects that result from a natural 20 attack roll.

If the attack was a melee attack, the attacker must make a CON save, flinching on failure. This flinch lasts for the rest of this turn and through the attacker's next turn.