Path of the Glacier

Born from the frigid and daunting Everglacier, barbarians who follow Path of the Glacier have learned to harbour the resolute stillness, patience, and unwavering determination and destruction of the icy landscape. These warriors transform their bodies into powerful moving bunkers that are as difficult to take down as they are to escape from.
Barbarians that follow this path are often trained hunters who enjoy the patient stalking of prey. They thrive on the peril they impose on their fleeing targets, and take special pride in their slow-and-steady approach.

Level 3 Features:

Permafrost.

Your skin becomes icy to the touch, outwardly manifesting the cold and patient well of power within you. You gain the following benefits.

Frosted Flesh: While you aren't wearing any armor, you gain a +1 bonus to AC.

Rage Extension: Whenever your Rage would end while you don't have the Unconscious condition, you can choose to extend it (no action required). You can use this feature a number of times equal to your Constitution modifier (minimum of once), and you regain all expended uses when you finish a Long Rest.

Resistance: You have Resistance to Cold damage.

Frostbite.

You can unleash the unforgiving cold inside of you with your attacks. Once on each of your turns while your Rage is active, you can choose to release a burst of sheer cold when you hit a target with a Strength-based attack. When you do, the target takes an extra 1d6 Cold damage from the attack. This extra damage increases by 1d6 when you reach Barbarian levels 9 (2d6) and 16 (3d6).
When a creature takes Cold damage in this way, its Speed is reduced by 10 feet until the start of your next turn.

Level 6 Feature:

Cold Fortress.

You learn to further channel the icy resilience within you. When you enter your Rage and aren't wearing any armor, your skin becomes shielded by a protective layer of frost. This frost grants you a number of Temporary Hit Points equal to 1d12 plus your Constitution modifier.
You can take a Bonus Action on your following turns while your Rage is active to expend a Hit Point Die and gain these Temporary Hit Points again.

Level 10 Feature:

Deep Sleep.

You can choose to enter a deep state of hibernation when you take a Long Rest. While resting in this way, you're cold to the touch and appear dead to all outward inspection and to spells or other magical effects used to determine your status. Noise and other distractions fail to wake you.
You awaken from this rest after 6 hours, when you take damage, or when a creature uses its action to slap you awake. If you finish a continuous 6 hours of sleep in this way, you gain the benefits of finishing a Long Rest, and you gain a special pool of Hit Dice, which lasts until the end of your next Long Rest and can be used as normal. This pool has a number of Barbarian Hit Dice in it equal to your Constitution modifier (minimum of 1 Hit Die).

Level 14 Feature:

Avalanche Stomp.

You become as mighty as an unstoppable glacier. As an action, you can stomp the ground to send out a tremor. Each creature of your choice in a 15-foot radius originating from you must make a Dexterity saving throw (DC 8 plus your Strength modifier and Proficiency Bonus). On a failed save, a creature takes Bludgeoning damage equal to 3d6 plus your Strength modifier, and it has the Prone condition.