Path of Magma

Magma barbarians channel the primal wrath of volcanic magma into combat with them to strike down their enemies

Level 3: Volcanic fury

You have resistance to fire damage and while your rage is active any weapon attacks you make can deal fire damage in place of the normal damage while still activating anything triggered by the original damage type. Once per turn while your rage is active you can also deal and additional damage die in fire damage. 

Level 6: Flaming aura

While your Rage is active, any creatures starting their turn within 10 feet of you take 1d6 fire damage

Level 10: Eruption

Once per rage you cause an eruption of magma wth a 10 feet emenation that goes 60 feet high dealing 4d8 points of fire damage to any creature that fails a dexterity saving throw with a DC equal to 10 + your proficiency bonus +your constitution modifier. The creatures take half damage in a success. (Unfortunately I couldn't find a way to get the DC to work so you have to calculate it manually)

Level 14: Overheat

When you are ragin you gain immunity to fire damage and resistance to cold damage. In addition all your attacks deal and extra 2d6 fire damage