Wyvern riders they are defined by their connection with a wyvern, but vary on the way they approach this connection. The wyverns are more than mere mounts, acting as extensions of the rider mind and body, fighting in unison and developing deep connections, that allow them to manifest incredible powers. For this very reason, they are a sight on the battlefield, inspiring fear and admiration on both allies and enemies.

Many of the elements from this subclass is taken from the dndwiki hombrew entry (Wyvern Rider).

 

Wyvern mount

Starting at 3rd level, you gain the services of a wyvern, that you have raised and trained since it was born. It is friendly to you and your companions, and it obeys your commands. See this creature's game statistic Bellow.

In combat, the wyvern acts independently of you, but it always obeys your command. In combat, i rolls initiative and acts on its own turn. It can't attack without your command to do so, but it can take other actions as normal. You can command your wyvern to attack as an action on your turn.

You can mount your wyvern. The initiative of a mounted wyvern changes to match yours when you mount it. You can only move to dismount your wyvern, while mounted. It moves as you direct it, and it has only three action options: Dash, Disengage, and Dodge. A mounted wyvern can move and act even on the turn that you mount it. All other rules of mounted combat apply. Your wyvern can still use its reaction to make an attack, at your command. While mounted, your wyvern is unable to fly, but it can use its wings to aid its jump, doubling its jump height.

 

Riders Bond

Starting at 3rd level, your mastery as a rider becomes apparent. You have advantage on saving throws made to avoid falling off your Wyvern. If you fall off your Wyvern and descend no more than 10 feet, you can land on your feet if you’re not incapacitated. mounting or dismounting a creature costs you only 5 feet of movement, rather than half your speed.

If your wyvern is slain by a creature, you gain advantage on all attack rolls against the killer for the next 24 hours. If the wyvern dies, you can perform a special ritual to bring it back to life. The ritual is performed as part of a long rest to summon his soul and regenerate his body.

Finally You can also use the magical bond between you and your wyvern to protect it from harm. While your wyvern is within 30 feet, when it takes damage, you can use your reaction to split that damage between you and your wyvern.

Ironclad Scales

Starting at 3rd level you have learned the process of how to create a powerful armor to protect your companion. You create a suit of armor adapted to your dragon, with the statistics of the full plate armor (AC 19).

In addition, you gain proficiency with martial weapons and your wyvern doesn't suffer any movement speed reduction if you are riding it while using armor.

Poisonous Sting

At 7th level, your wyvern has developed the glands to produce venom. A creature that takes damage from the attack with the stinger of the wyvern must make a Constitution saving throw. The saving throw to resist the poison is equal 8 + your proficiency bonus + the wyvern's Constitution modifier.

On a failed save, the target takes poison damage equal to 3d6, or half as much on a successful one. This feature can be used a number of times equal to your wyvern's Constitution modifier (minimum once). Once the wyvern has spent all his uses of this feature, it cannot do so again until you finish a long rest.

The poison damage increases in 1d6 when you reach the 8th level (4d6), 11th level (5d6), 14th level (6d6) and 17th level (7d6).

Terror From Above

At 11th level, you have trained your wyvern into mastering its flying skills. your wyvern can carry you while walking without any reduction on its movement speed, and while flying with half of his movement speed. Your wyvern no longer needs to end his turn on the ground and you can also perform quick aerial maneuvers with your wyvern. When you attack a creature during the flight movement of your wyvern, this movement doesn't provoke opportunity attacks for entering or leaving the reach of a creature.

In addition, your wyvern can now uses its claws to attack. Once in each of your turns, you can command your wyvern to replace one of his attacks with the claw attack, dealing damage equal to 2d6 + his Strength modifier. The damage increases to 2d8 when you reach 17th level.

Sentinel Command

At 15th level whenever a creature enter or leave a space within 5 feet of your wyvern, you can command it to use its reaction to make an opportunity attack. You must be able to communicate the command to your wyvern, and this feature doesn't require you to take any action

In addition an attacker that your wyvern can see hits it with an attack, it can use its reaction to halve the attack’s damage against it.

Aerial Charge

At 18th level, If your wyvern flies for at least 20 feet, you can make an aerial charge. You command your wyvern to attack with its claws and if successful the target must make a Strength saving throw against a DC equal to 8 + your proficiency bonus + the wyvern's Strenght modifier. On a success, you can snatch a medium or smaller creature from the ground and carry it with you. At any point during your movement you can choose to drop it and the creature will then take fall damage equal to 1d6 for each 10 feet you move with it.