Oath of the Nine

Just as the Gods have Paladins devoted to championing their causes, so too do the Archdevils of the Nine Hells, perhaps the most notable of them being the God-Fiend, Asmodeus, having attained godhood himself. 

Paladins who swear their oath to an Archdevil are typically Lawful Evil, much like the Fiends they serve. They spread their Lord's influence across their Planes, corrupting and damning the souls of mortals they deal with, some are even tasked with brokering deals on behalf of their Lord, as well as the collection of souls owed by participants of these deals.

Channel Divinity

When you take this oath at 3rd level, you gain the following two Channel Divinity options.

Infernal Smite. As a bonus action, you imbue your weapon with Infernal flames. For 1 minute, all radiant damage dealt by your smites is instead fire, and the bonus 1d8 damage of your Divine Smite is dealt to Celestials rather than Fiends. 

Call Devil. As an action, you utter a profane incantation to call forth a number of Devils from the Nine Hells. The Devils called are friendly to both you and your allies, and remain under your control until you use an action to dismiss them, or until you die. In either event, they then return to their home layer in the Nine Hells. The Devils share your initiative and take their turns immediately after yours, and will obey your commands (no action required by you). In the absence of any commands, they will attack the nearest enemy they can see.

You may call, and control, a number of Devils equal to your Charisma modifier (minimum 1), and they may be of a CR no greater than your Paladin level minus your Proficiency Bonus.

Oath Spells

You gain oath spells at the paladin levels listed.

Oath of the Nine Spells

Aura of Hellfire

Starting at 7th level, hostile creatures that begin their turns within 10 feet of you take 1d4+(your level in this class) fire damage while you are conscious.

At 18th level, the range of this aura increases to 30 feet.

Unholy Resilience

Beginning at 15th level, you have resistance to Bludgeoning, Piercing, and Slashing damage from Non-magical attacks.

Defiance

At 20th level, as an action, you can emanate an aura of defiance. For 1 minute, you and friendly creatures within 30 feet of you have advantage on all saving throws. 

In addition, for the duration, fire damage dealt by you (including your Hellfire Aura) and your allies ignores resistance and treats immunity as resistance.*

Once you use this feature, you can’t use it again until you finish a long rest.

*This resistance is not ignored by this feature.