Path of the Doom Slayer

In the first age, in the first battle, when the shadow first lengthened, one stood. Burned by the embers of Armageddon, his soul blistered by the fires of Hell and tainted beyond ascension, he chose the path of perpetual torment. In his ravenous hatred he found no peace; and with boiling blood he scoured the Umbral Plains seeking vengeance against the dark lords who had wronged him. He wore the crown of Night Sentinels, and thise that tasted the bite of his sword named him... the Doom Slayer,

Armored Destroyer

Starting at 3rd level, you gain proficiency in heavy armor, and you still gain the benefits of any barbarian features that would be excluded, even while wearing heavy armor.
Adittionally, anytime you score a critical hit on a creature with a melee weapon while you are raging, they must succeed in a con save(8+profficiency+str) or be stunned until the end of your next turn.

Rip and Tear

Beginning at 6th level the doom slayer exhibits barbarous cruelty against their foes. If the doom slayer hits an enemy within 5ft and reduces their Hp to 10 or less The doom slayer can make a grapple check on the target. On a succes you execute the target reducing their hp to 0. At 10th level this threshold increases to 15 or less HP and at 14th level it increases to 20 or less HP.

Argent Feast

Starting at 10th level, whenever you critically hit a hostile creature or reduce a hostile creature to 0 hit points on your turn, you can use a bonus action to regain a number of hit points equal to half your barbarian level.

Blood for Blood

When damaged by an enemy, you can use a reaction to spend hit dice, up to your max rages(unlimited at lvl 20), to negate that amount of damage.

Roll hit dice, and add con modifier as usual on short rest, and subtract that from the incoming damage.

If you reduce the damage to 0, and the attacker is within reach, you can make an attack as part of the reaction against that target.

You can use this feature as long as you have hit dice to spend.