Demon's Mage

Your powers are amplified since your master resides on the same plane as you.
Long ago a rip in the planes allowed this demon to leave the lower planes through the plane of fire and enter the material plane.
After arriving they were able to anchor themselves to a volcano fueled by the plane of fire through dark rituals and blood.

They only desire that their followers burn their foes.
They do not deny their followers weapons but they demand the killing blow be incendiary.

They also demand the same death for their followers.
Demon's Mages are bent by Fate to always die by fire.

Expanded Spell List

The Demon Mage lets you choose from an expanded list of spells when you learn a warlock spell.
When selecting spells you may choose freely from the Fiend, Genie, Efreeti, Great Old One, Hexblade, Undead, or Undying Expanded Spell Lists.

Hellbent

Starting at 1st level, whenever you use your last spell slot that spell deals its maximum possible damage without rolling.

Lava Touched

Starting at 6th level, you gain resistance to fire damage. In addition you are accustomed to hot temperatures and do not need to make Constitution save for exhaustion in hot environments.

Rain of Gore

Starting at 10th level, as an action you can summon a hail of blood and body parts to the ground in a 120-foot-radius, 400-foot-high cylinder centered on a point within a range of 200 feet. Each creature in the cylinder must make a Dexterity saving throw DC 18. A creature takes 2d8 bludgeoning damage and 4d6 necrotic damage on a failed save, or half as much damage on a successful one.

Any creature that starts its turn within 60 feet of the Rain of Gore must make a Constitution saving throw DC 10 or becomes Frightened of the area of effect. The creature can reattempt the save at the start of its turn.

The area of effect becomes difficult terrain.

You may use this ability and number of times equal to you Charisma modifier (min 1). You regain expended uses when you finish a long rest.

A Demon’s Embrace

Starting at 14th level, you may cast Summon Fiend as a 6th level spell with a few changes.

• the spell does not require concentration
• you must pick demon
• you are polymorphed into the fiend instead of it being summoned

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