Oath of the Dragon's Bane

Paladin's of the Oath of the Dragon's Bane have no laws to their oath. Their only law is to protect every dragon of bahamut, or Tiamat if that's their Deity. They are masters of spells relating to dragons, such as fire, acid, or lightning spells. But they are friend to all dragons, good or bad, and dragons can count on them.

They are limited to The deities of Kobolds and Dragonborn. Your Dm may lift this restriction to better suit their campaign. 

Dragon's Divinity

At 3rd level, you gain 2 channel divinity options.  

Dragon's Bane
At 3rd level, you may use an action to  breathe fire in a 15ft cone. The opponent must make a constitution saving throw. On a success, they take no damage. on a failure, the targets takes 3d6 damage of Acid , lightning or fire, your choice when you use the Dragon's bane.

Dragon's Fear
At 3rd level, you may use an action to breathe fear into your enemies. You may breathe fear In a 30 ft straight line. This ignores cover. The targets must make a charisma saving throw or be frightened of you for 10 minutes.

In addition, instead of gaining additional spells, you gain a gift from your deity. Choose from the Blessing of Bahamut, which adds your proficiency to your AC, or the Tyranny of Tiamat, which gives you a natural weapon in the form of claws.

 

Blessing of Bahamut

You gain a bonus to your AC equal to your proficiency Modifier.

Tyranny of Tiamat

You gain a natural weapon in the form of claws. These do 2d12 Necrotic damage, and have the finesse and light properties.

Dragon's Companion

At 7th level, you gain a companion from your Deity. You may choose from a silver, blue, copper, bronze, brass, black, red, or green Dragon wyrmling. Add you proficiency bonus to its AC, Attack rolls, Damage rolls, and it's health is it's natural health or 4 times your paladin level, whichever's higher. You may use a bonus action to command it to attack, disengage, help, dash, or take any actions it could normally take, but it doesn't benefit from Multiattack. If you don't command it, it takes the dodge action. If you are unconscious or otherwise incapacitated, it works to preserve you and itself, putting you first. It may make Death saving throws if it is knocked unconscious. If it dies, you may gain a new one by spending 8 hours in prayer and repentance to gain a dragon egg, the color of the dragon wyrmling you want. It hatches in 1d10 days. If you roll a 1, it hatches after your next short rest.

Dragon's Lair

at 15th level, after a long rest, you may designate your wyrmling's lair. It must be within 60 ft of where you took the rest, and it allows the wyrmling to take lair actions, as normal.

Dragon's Life

At 20th level, you may age your dragon up to an Adult Dragon. In addition, you do not age, suffer none of the frailty of old age, and can't die unless your dragon is dead too.