Undead Fortitude. If damage reduces the zombie to 0 hit points, it must make a Constitution saving throw with a DC of 15, unless the damage is radiant or from a critical hit. On a success, the zombie drops to 1 hit point instead.

Unarmored Defense. While they are not wearing any armor, the barbarian's Armor Class equals 10 + its Dexterity modifier + its Constitution modifier. It can use a shield and still gain this benefit. (Reflected in Stat Block)

Danger Sense. The barbarian has advantage on DEX saving throws that they can see, including traps and spells.

Rage. Entering a rage is a bonus action. While raging, the barbarian gains the following benefits if they aren't wearing heavy armor:

They have advantage on all Strength checks and Strength saving throws.
When they make a melee weapon attack using Strength, they gain a (+2) bonus to the damage roll.
The barbarian gains resistance to all bludgeoning, piercing, and slashing damage.
Rage lasts for 1 minute. It ends early if they are knocked unconscious or if their turn ends and they haven't attacked a hostile creature since their last turn or taken damage since then. They can also end their Rage state on their turn as a bonus action.

Reckless. At the start of its turn, the barbarian can gain advantage on all melee weapon attack rolls during that turn, but attack rolls against it have advantage until the start of its next turn.

Dark Magic. The barbarians body and weapons have all been imbued with Dark Necrotic Magic, giving an extra 2D8 Necrotic damage.

Extra Attack. The barbarian can make three attacks of melee or ranged.

Slam. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 8 (1d12 + 1) bludgeoning damage, +2D8 Necrotic damage.

Greataxe. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 16 (1d20 + 3) slashing damage, +2D8 Necrotic damage.

Handaxe. Ranged Weapon Attack: +4 to hit, range 20ft., one target. Hit: 9 (1d12 + 1) slashing damage, +2D8 Necrotic damage.