Copycat

Using intense observation and a photoreflective memory training, the fighter can become a master of using the techniques of others for their own use. 

Copycat's Reflexes

Beginning when you choose this archetype at 3rd level, you gain expertise in Perception and History, as well as the ability to copy any melee or ranged attack made against you in the last round. You may use this ability a number of times equal to your Intelligence modifier

Copycat Strike cannot crit. 

Skilled Fighter

Starting at 7th level, you can add half your proficiency bonus (round up) to any Strength or Dexterity based attack rolls, and initiative checks.

Adaptive Fighting

At 10th level, you gain the benefits of any fighting style a creature you have fought in the past or have watched fight (History check, DC18 if using watching) has used, until the end of combat. You may use this ability once per round as a FREE action, but can only have one fighting style active at a time this way, and can only use this once per round.

Archery

You gain a +2 bonus to attack rolls you make with ranged weapons.

Defense

While you are wearing armor, you gain a +1 bonus to AC.

Dueling

When you are wielding a melee weapon in one hand and no other weapons, you gain a +2 bonus to damage rolls with that weapon.

Great Weapon Fighting

When you roll a 1 or 2 on a damage die for an attack you make with a melee weapon that you are wielding with two hands, you can reroll the die and must use the new roll, even if the new roll is a 1 or a 2. The weapon must have the two-handed or versatile property for you to gain this benefit.

Protection

When a creature you can see attacks a target other than you that is within 5 feet of you, you can use your reaction to impose disadvantage on the attack roll. You must be wielding a shield.

Two-Weapon Fighting

When you engage in two-weapon fighting, you can add your ability modifier to the damage of the second attack.

Superior Copy

Starting at 15th level, your copycat attacks score a critical hit on a roll of 20

Copycat's Resilience

At 18th level, you attain the pinnacle of resilience in battle. At the start of each of your turns, you regain hit points equal to 5 + your Constitution modifier if you have no more than half of your hit points left. You don’t gain this benefit if you have 0 hit points.