Fire Domain

Here is my attempt on splitting the fire cleric from the light cleric. The light cleric keeps all his features but gets a lot more divination spells for the spell list and loses the fire spells.

The fire cleric is driven by purging the evil with force and flames. In order to make the world a better place one must burn and experience enlightenment through the searing pain of his holy flames. Even the fire demons cannot withstand his pure belief of purifying flames and fire.

Bonus Cantrip

When you choose this domain at 1st level, you learn the Control Flames Cantrip, if you don't already know it. 

Heart of the Flame

Also on 1st level you can give the blessing of fire to your companions, steeling them for the battles ahead. You can use your action to touch a willing creature (other than yourself) to give it temporary hitpoints equal to your level. The creature has resistance to fire damage as long as it has these hitpoints. You can't use this feature on undead creatures or constructs.

Once you use this feature, you can't do it again until you finish a short or long rest.

 

 

Channel Divinity: Purifying Flames

Starting at 2nd level, you can use your Channel Divinity to purify the body and the soul of those you burn.

When you deal fire damage to a creature with a cleric spell, you can purge a single creature you dealt damage to. You effect the creature either with the Lesser Restoration or the Dispel Magic spell without casting it.

Blessed by fire

You gain resistance to fire damage.

Wrath of the Holy Flames

Also at 6th level your holy flames burn those, who are the greatest evil.

Your cleric spells ignore fire resistances of fiends and undead.

Potent Spellcasting

Starting at 8th level, you add your Wisdom modifier to the damage you deal with any cleric cantrip.

Improved Purifying Flames

At 17th level you can choose to effect the creature with Greater Restoration  instead of the Lesser Restoration spell.

Neverending Fire

At 17th level the heat of your faith keep you alive even when you receive a fatal blow.

When you are reduced to 0 hitpoints you can chose to drop to 1 instead. If you do so you get temporary hitpoints equal to your level. Then every creature of your choice in a 30-foot radius must make a Constitution saving throw, taking 4d10 fire damage on a failed one and half of that on a successful one.

Once you use this feature you can't do so again until you finish a long rest.