Oath of flames

Your hatred of evil is so strong that it has developed physical power

Channel Divinity

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

Flaming weapon. As an action, you can imbue one weapon that you are holding with angry energy, using your Channel Divinity. For 1 minute, The weapon deals an extra 1d4 + your Charisma modifier fire damage evil creatures who take this damage takes triple the damage. the extra damage becomes 1d6 when you reach level 7 in this class.  

You can end this effect on your turn as part of any other action. If you are no longer holding or carrying this weapon, or if you fall unconscious, this effect ends.

Pyro bolt.  You throw a burning bolt of divine fire at 1 creature you can see within 500 feet. You can use an action to throw the bolt at a creature within 500 feet of you that creature must make a dexterity save against your spell save dc or take 1d4 fire and 1d4 radiant damage the damage deals double to evil creatures. the fire and radiant damage increases to 1d6 when you reach 7th level, and to 1d8 when you reach 15th level

Burning revenge. As a reaction to taking damage you can choose to deal fire damage equal to your proficiency bonus + your charisma modifier to the creature who damaged you. you can use this feature a number of times equal to half your level. 

Oath Spells

You gain oath spells at the paladin levels listed.

Oath of Devotion Spells

Fire soul

You gain resistance to fire damage, when you reach 11th level you gain immunity to fire damage and resistance to cold damage.

Aura of Anger

Starting at 7th level, you and friendly creatures within 10 feet of you gain advantage on attack rolls and intimidation checks while you are conscious.

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

Fiery sacrifice

Beginning at 15th level, you can use your action to call upon the power of your god to sacrifice yourself for the good of others. You can use your action to drop to zero hit points when you do this you create a giant explosion in a 150 foot sphere centered on yourself all non-good creatures in the area take 15d10 fire damage and15d10 radiant damage and all good creatures in the area regain 15d10 hit points.

Burning form

At 20th level, you can become a physical empowerment of fire. as an action you can become a fire elemental myrmidon for 10 minutes. while in this form you retain your intelligence, wisdom, and charisma; your spells, your class features, and your proficiencies.