Guardian

Guardians are the first and last line of defense, an immovable wall against outside forces. Though they often fight alongside others in large-scale battles, their knowledge of how to exploit natural chokepoints and create zones of control allow them to excel defending terrain on their own.

Level 3: Guardian Training

You gain an uncanny sense of when things aren't as they should be, giving you an edge when you dodge perils. You have Advantage on Dexterity saving throws unless you have the Incapacitated condition.

Furthermore, your Hit Point maximum increases by 3, and it increases by 1 whenever you gain another Fighter level.

Level 3: Defensive Stance

As a Bonus Action, you can spend one use of Second Wind to enter a Defensive Stance. This stance lets you focus on protection and resilience, at the cost of mobility. While active, your Defensive Stance follows the rules below.
Damage Resistance. You have Resistance to Bludgeoning, Piercing and Slashing damage.
Armor Class Bonus. You gain a +2 bonus to your Armor Class.
Advantage on Saves. You have Advantage on all saving throws.
Restricted Mobility. Your Speed is reduced by half. Your Long Jump and High Jump distance is also halved.
Duration. The Defensive Stance lasts until the end of your next turn, and it ends early if you make the Dash action or have the Incapacitated condition. If your Defensive Stance is still active on your next turn, you can extend it by doing one of the following:

• Make an attack roll against an enemy
• Take at least 1 point of damage from a hostile creature
• Force an enemy to make a saving throw
• Take a Bonus Action to extend your Defensive Stance

Each time the Defensive Stance is extended, it lasts until the end of your next turn. You can maintain a Defensive Stance for up to 1 minute.

Level 7: Phalanx Training

Your training in large-scale battles helps you and your allies defend yourselves better. You gain the following benefits.
Bulwark. When you are within 5 feet of an ally wielding a shield, all squares within 5 feet of both of you are treated as if granting Half Cover.
Intercept. Once per round when an enemy would provoke an Opportunity Attack, you can execute it without spending your Reaction to do so. You can do this a number of times equal to your Intelligence modifier and you recover all uses upon completing a Long Rest.
Vigilance. All squares within your Reach are considered Difficult Terrain to any creatures hostile to you.

Level 10: Uncanny Dodge

When an attacker that you can see hits you with an attack roll, you can take a Reaction to halve the attack's damage against you (round down).

Level 15: Persistent Defender

When you roll Initiative, you regain Hit Points as if you spent a use of Second Wind (even if you have no uses left) and regain all expended uses of Second Wind. After you regain uses of Second Wind in this way, you can't do so again until you finish a Long Rest.

In addition, your Defensive Stance is so intense that it now lasts for 1 minute without you needing to do anything to extend it from round to round. Your Defensive Stance ends early if you have the Unconscious condition (not just the Incapacitated condition).

Level 10: Improved Defensive Stance

Your Defensive Stance grants you greater protection capabilities. You gain the following benefits while your Defensive Stance is active.
Enhanced Defenses. You gain an additional +1 to your Armor Class, for a total of +3.
Endurance. If you drop to 0 Hit Points while your Defensive Stance is active and don't die outright, you can use your Second Wind as a Reaction.
Immovable Wall. You gain Resistance to Force damage.

Level 18: Superior Defensive Stance

Your Defensive Stance reaches its pinnacle, giving you the following benefits while it is active.
Master Defenses. You gain an additional +1 bonus to Armor Class, for a total of +4.
Mental Resilience. You gain Resistance to Psychic damage.
Mobile Defense. Your Speed, High Jump and Long Jump distances are no longer reduced.