Rage
PHB p46
In battle, you fight with primal ferocity. On your turn, you can enter a rage as a bonus action.
While raging, you gain the following benefits if you aren't wearing heavy armor:
You have advantage on Strength checks and Strength saving throws.
When you make a melee weapon attack using Strength, you gain a +2 bonus to the damage roll. This bonus increases as you level.
You have resistance to bludgeoning, piercing, and slashing damage.
If you are able to cast spells, you can't cast them or concentrate on them while raging.
Your rage lasts for 1 minute. It ends early if you are knocked unconscious or if your turn ends and you haven't attacked a hostile creature since your last turn or taken damage since then. You can also end your rage on your turn as a bonus action.
Once you have raged the maximum number of times for your barbarian level, you must finish a long rest before you can rage again. You may rage 2 times at 1st level, 3 at 3rd, 4 at 6th, 5 at 12th, and 6 at 17th.
Unarmored Defense
PHB p46
While you are not wearing any armor, your Armor Class equals 10 + your Dexterity modifier + your Constitution modifier. You can use a shield and still gain this benefit.
Great Weapon Master
PHB
p167
You've learned to put the weight of a weapon to your advantage, letting its momentum empower your strikes. You gain the following benefits:
On your turn, when you score a critical hit with a melee weapon or reduce a creature to 0 hit points with one, you can make one melee weapon attack as a bonus action.
Before you make a melee attack with a heavy weapon that you are proficient with, you can choose to take a -5 penalty to the attack roll. If the attack hits, you add +10 to the attack's damage.
Source: PHB, page 167
Path of the Ancestral Guardian
XGE p9
Some barbarians hail from cultures that revere their ancestors. These tribes teach that the warriors of the past linger in the world as mighty spirits, who can guide and protect the living. When a barbarian who follows this path rages, the barbarian contacts the spirit world and calls on these guardian spirits for aid.
Barbarians who draw on their ancestral guardians can better fight to protect their tribes and their allies. In order to cement ties to their ancestral guardians, barbarians who follow this path cover themselves in elaborate tattoos that celebrate their ancestors' deeds. These tattoos tell sagas of victories against terrible monsters and other fearsome rivals.
Ancestral Protectors
Starting when you choose this path at 3rd level, spectral warriors appear when you enter your rage. While you're raging, the first creature you hit with an attack on your turn becomes the target of the warriors, which hinder its attacks. Until the start of your next turn, that target has disadvantage on any attack roll that isn't against you, and when the target hits a creature other than you with an attack, that creature has resistance to the damage dealt by the attack. The effect on the target ends early if your rage ends.
Class/Racial Features & Traits