Path of The Myrmidon

The Myrmidon. You are not a cutesy totem follower, or a wizard pretender, and not even a raging berserker. You are part of a greater legacy. You fight for glory, for Domination! Myrmidons are siege engines made flesh, soldiers who conquer battlefields through sheer physical prowess and an unyielding will. Encased in heavy armor, knuckles hardening from countless strikes, these warriors become the literal wall against which enemies break. Grappling, staggering, and pummeling their foes, a Myrmidon controls the flow of the stride, choosing whom to destroy first, and whom to spare. All that while ignoring punishment that would fell lesser soldiers. Some say a Myrmidon's resolve is made of pure iron; others say it borders on madness. Whatever the truth, when a Myrmidon enters the fray, the battlefield trembles under their advance.

Several subclass features allow you to impose a save against your target. Unless stated otherwise the save DC for these features is 8 + proficiency modifier + strength modifier.

Fists Of The Pugnator.

 At 3rd level, your fists are steel, yet your soft innards need protection.

• Unarmed Strikes. Your unarmed strikes deal 1d8 bludgeoning damage + your strength modifier. The damage die increases when you reach certain barbarian levels (1d10 at level 10, 1d12 at level 14). Your unarmed strikes count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks.
  When you reach barbarian level 10, your unarmed strikes count for and trigger the Great Weapon Fighting fighting style and Great Weapon Master feat regardless of wording if all your hands are free.

 

• Grappling Strike. Grappling Strike. Whenever you hit a creature with an unarmed attack, you can immediately attempt to grapple it as a free action. When you attempt to grapple a target in this way, the DC of the target's saving throw is equal to your attack roll.

Additionally, while raging, you deal additional damage on unarmed strikes against a creature grappled by you. This damage is equal to your rage bonus.

As a bonus action, you can attempt to cripple a creature you have grappled using this feature. The creature must make a Constitution saving throw against your Myrmidon DC. On a failed save, your attacks score a critical hit against it on a 19 or 20 until the grapple ends.
You can use this feature a number of times equal to your Strength modifier (minimum of once) per long rest.

• Hard Shell, Soft Insides. You gain heavy armor proficiency and you can rage while wearing heavy armor.

Etiam

At 6th level, you wish to continue on. Etiam! MORE!

Whenever you successfully cripple or grapple a creature using the features granted by this subclass, you can make one additional unarmed attack called Nunc immediately. If Nunc hits, the die for the unarmed strike is replaced with its maximum value, and the creature must make a Constitution saving throw against your DC or be stunned until the start of your next turn.

Nunc can be used an amount of times equal to your proficiency bonus per short or long rest.
Nunc can only be used once per turn on the same creature.

You additionally can use the Fast Movement class feature while wearing heavy armor.

Infirmus!

At 10th level, you see that your enemies are weak. Paper dolls you can throw around. 

If you move at least 15 feet towards a target immediately before targeting it with an unarmed strike, you can force it to make a STR saving throw. The DC of this save is equal to one attack roll with your unarmed strike. On a failure, both you and the target receive the prone condition. If you stand up, the creature is also no longer considered prone. While prone in this way, your attacks against the target always have advantage.

Incontintens!

At 14th level, realization that you're incredible continues crawling into you. 

While raging and wearing heavy armor, you don't suffer penalties from difficult terrain or any movement reduction that affects your speed, outside of conditions that set your speed to 0.

While raging, you may take a bonus action to enter the Incredibilis state for the remainder of your rage. When taking the attack action while in this state, you may make an additional number of unarmed strikes up to half your proficiency bonus. Each of these strikes triggers a shockwave, causing all creatures within a 10ft emanation of the target (including yourself) to take additional damage equal to your proficiency bonus + your strength modifier. You must then expend and roll a hit die for each of these strikes, taking damage equal to the number rolled. This damage cannot be reduced or negated in any way.

Incredibilis ends prematurely if you have no more Hit Dice to expend. If you are removed from the state in this way, you must succeed a DC 25 constitution saving throw or suffer a level of exhaustion.

Once you use this feature, you can't use it again until you finish a Long Rest unless you expend a use of your rage (no action required) to restore your use of it.