Path of the Rider

Tabor regarded the tracks imprinted on the muddy field with a pair of fingers, outlining the divot in the plains. He brought the fingers to his nose. 

"Orcs," he grimaced and spat into the ground. 

Devon regarded him gravely. "Are you sure?"

Tabor grunted his reply. "They're not far off. Maybe an hour." He turned to Devon, his eyes flashing with rage. "If they reach the camp before daybreak, the tribe will bleed."

"Then we must not let them." Devon replied flatly, but his blood was full of fire as well. He turned his steed sharply and launched forward. The chestnut-colored warhorse of his people was bred for speed, forged for battle. More light and agile than the workhorse of the field; less mass than the warhorses to the north. When spurred, It was the wind. When provoked, it was the storm. 

Tabor sprung from his perched stance following his brother. Without hesitation or command, his own mount was there. He was already plucking his spear from its sheath as he spun upward into the saddle in one fluid motion, his horse already on the move before he'd settled into the stirrups. He and the horse were one, just as his people had lived for thousands of years. His were the unbowed people; the Riders of the Kyrn. His enemy would fall at the edge of his blade and under the hoofs of his horse, just as all who dared to spoil their sacred plain did. 

He let out a loud battle cry... and they were off. As Tabor pushed to meet his brother, Devon smiled, crazed and wild. Devon loosed an axe in his hand, his blood pulsing through his veins, shutting out all reason save the hunt and the kill. Beneath them, the hoofs on the ground sounded like thunder. 

They would kill tonight. And, if they were lucky enough to survive, they would feast after. 

If they were lucky.

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The Path of the Rider utilizes mobility and mounted combat to capitalize on a barbarian's strengths.

Your clan or tribe have developed unmatched equestrian skill as part of your culture or lifestyle, often developing a symbiotic relationship with your mount. Dedicated riders can form a bond with their mount, allowing the barbarian to move and act in unison with it. The Rider may perform dazzling tricks in the saddle, or ride standing up to dive headlong into combat from horseback. The mount of a barbarian who chooses this path can become as enraged as its owner, wading into combat with hoof or claw, or charging headlong into a sea of enemies, trampling them underfoot. 

This subclass can be used to represent a variety of barbarians in your world. They may be riders of the plains  who favor light, fast horses, or armored warriors who prefer heavy armored warhorses to charge into battle. They may be barbarians who worship flying mounts such as griffons or dragons as totemic idols in their society, bonding their spirits with the mount of their choosing. Be sure to check with your Dungeon Master on how this subclass might best fit into their setting.

Frenzied Rider

Starting when you choose this path at 3rd level, you become more adept at handling a mount in combat. You gain proficiency in Animal Handling if you don't possess this skill already, or gain Expertise in this skill if you do. Once during your move, you can mount a creature that is within 5 feet of you, or dismount without any cost in movement. You cannot mount a creature if you are incapacitated. 

You gain an advantage to Acrobatics (Dexterity) or Athletics (Strength) checks while mounted. If an effect moves your mount against its will while you're on it, you gain an advantage to succeed on a DC 10 Dexterity saving throw to avoid falling off the mount. You cannot land prone if you fall off your mount.

If your mount is knocked prone, you can use your reaction to dismount it as it falls and land on your feet. Otherwise, you are dismounted in a space within 5 feet it, but are knocked prone.

 

Improved Mounted Combat

At 6th level, you may add your Dexterity modifier to your mount's Armor Class if you are mounted. Your mount gains an advantage vs becoming frightened, or from being charmed or controlled by anyone other than you.

A controlled mount may use its action to Help, in addition to its other available actions.

Charge!

At level 10, you may spur your mount to charge into battle. 

Your mount may Attack with its action and may use any multiattack options available to it.

A controlled mount gains the Charger feat. When your mount uses its action to Dash, it can use a bonus action to make one melee weapon attack or to shove a creature. If the mount moves at least 10 feet in a straight line immediately before taking this bonus action, the mount either gains a +5 bonus to the attack’s damage roll (if you chose to make a melee attack and hit) or push the target up to 10 feet away from you (if you chose to shove and you succeed).

 

Rider's Bond

At level 14, you have developed a special bond with your mount.

If your mount is hit by an attack, you may use your reaction to make an Animal Handling skill check contested by the roll of the attack. If you succeed, your mount takes no damage instead.

You may use your Action to heal your mount. You may use any number of your unspent hit dice to heal your mount. You must take a long rest before you can use this ability again.