Path of the Titan Breaker

In the frozen northern reaches, a giant looms over an unsuspecting village. In the deepest jungles a great beast tears down trees with a swing of its arms. In the depths of a mountain cave a dragon lies among its hoard, plotting its next raid. Titanic threats, big enough to crush poorly made fortifications and break men in two. But in such areas where these creatures exist in great numbers their presence often gives way to a counter balance. The iron clad Titan Breaker and their massive blades.

Barbarians who follow this path have trained their whole life to stand against threats that are larger then life and take up their arms as their own. Titan breakers know that even the strongest body can be broken so- unlike most barbarians- they eschew shields and clad themselves in armor to become walking unstoppable forces. But even encased in steel their fury knows no bounds, and they leverage both their rage and the sturdiness of their armor to stand undaunted in the face of much large creatures. They often adorn their helms with visages of such beasts and monsters and take their weapons from slain giant foes, and always cut an imposing and intimidating figure.

Armored Berserker

The Titan Breaker Barbarians know that only the strongest of fortifications can stand against their larger than life foes. When you choose this subclass at 3rd Level you gain Heavy Armor Proficiency, but lose the ability to properly use a shield while raging. In addition, while raging and wearing heavy armor, you add your Consitution modifier to your AC. This bonus can not exceed your proficiency bonus. Starting at 14th level, you add your full Consitution Modifier to your AC while raging and wearing heavy armor regardless of your proficiency bonus.

Jotungrip

To pierce through the thick hides of their hated foes, Titan Breakers learn to leverage their strength and the weight of their armor to wield blades far too big for most mortals. Beginning at 6th level you do not roll with disadvantage when wielding a weapon that is sized for a creature one size category larger then you while raging.  You must use both hands to wield an oversized weapon in this way, and can not wield an oversized weapon with the Two-Handed tag. If the oversized weapon has the Versatile tag, you do gain the benefits of that tag while wielding the weapon. You may also draw a weapon as a part of the same action that you use to enter your rage.
In addition, when wielding a weapon two handed while raging you critically hit on a 19-20.

Unstoppable Slayer

Between the weight of your armor and your sheer strength a Titan Breaker can not be impeded. Starting at 10th level you ignore difficult terrain. In addition, If a spell or ability would push, pull or knock you prone without a saving throw you may make a Strength Saving Throw with a DC equal to the distance you would be moved (being knocked prone is DC 15). If you succeed, you do not move and remain standing in your current square. If the spell or ability does allow for a saving throw, you instead only move half the distance on a failed save (you are still knocked prone on a failed saving throw against an effect that would knock you prone).
Finally, you may use your reaction to allow an adjacent ally to use the result of your saving throw instead of their own in response to a spell or ability that would push, pull, or knock them prone.
Once you have used this ability a number of times equal to your proficiency bonus, you may not use this ability again until you finish a Long Rest.

Slayer's Redoubt

Even in the face of a Dragon's Fire, the Titan Breaker can weather any assault. At 14th level if you are within an area of effect that would normally allow for a saving throw to resist damage while raging (such as a fireball or a dragon's breath weapon), you may treat all damage dice rolled as if they had been 1s, taking the minimum damage from the spell or effect. This choice may be made after the result of the saving throw is revealed. You can only use this ability once per long rest.