Longsword Master

With your use and training with a longsword, you are now considered a master with this weapon. In order to use the aspects of this feat you will have to equip a longsword. Any DC prompted by this feat is equal to 8 + your proficiency bonus + your Strength modifier. You must use a bonus action to enter and exit a stance unless transitioning. In order to use the two handed strikes while in a stance you must have your offhand empty.  

When using the weapon with one or two hands: 

Low Grip Stance: This defensive stance allows you to better deflect opponents strikes as you hold the blade in a reverse. When you take this stance to bolster your AC by +3, in addition you may attempt to prevent an enemy melee attack by using a reaction. The weapon hit sets the DC, roll a D20 and add your attack modifier. If you succeed the DC the damage is reduced to 0. If the attacker is using a two handed weapon, damage is reduced by half. While in this stance any attacks you make have disadvantage. 

Low Grip Stance Transition Bonus: When you enter this stance from Clearing Strike you double the AC bonus from Low Grip Stance until the beginning of your next turn.

Medium Grip Stance: This balanced stance allows you to control your opponents movements. If you are grappled you may use one of your attacks to break out of the grapple with a DC equal to the opponents AC instead of using an action to break the grapple. The attack does no damage. In addition you may use a reaction to grapple a creature one size greater or smaller than you that enters your threat radius. 

Medium Grip Stance Transition Bonus: When you enter this stance from Clearing Strike or Exposing Strike your threat radius expands 5ft until the beginning of your next turn.

High Stance:  When in this stance you use your bonus action to make an additional attack with your main weapon. While in this stance if your natural roll is below a 8 it is considered an 8. In addition if you perform a critical hit while in this stance you gain an additional attack once per turn. While in this stance because you are focused on offense you allow yourself to be exposed, attacks against you have advantage. 

High Stance Transition Bonus: When you enter this stance from Exposing Strike your next attack gain an addition 2d8 damage dice. 

When using this weapon with two hands: 

Clearing Strike: If you are in the Low Stance you cannot use this strike. Using a bonus action you may make the next strike a Clearing Strike, this must be declared before you roll to attack. You spin the blade between yourself and your opponent. If this attack hits, your movement does not provoke attacks of opportunity from this opponent. You must transition to a lower stance by one position (High to medium, medium to low).

Grappling Feint: As a reaction taunt an enemy to attack you. Choose an enemy within 15ft of you to make a Char saving throw. If they fail, they will proceed toward you and attack you. When they do, you may attempt to grapple and disarm them. If the creature is larger in size than you are or if their weapon is part of their body you will not be able to disarm them. 

Exposing Strike: If you are in the High Stance you cannot use this strike. As a bonus action you may make the next strike an Exposing strike, this must be declared before you roll to attack. If your next weapon attack hits, your target must make a strength saving throw. If they fail, the next attack has advantage against them and their next attack has disadvantage. You must transition to a higher stance by one position (low to medium, medium to high).