Sage of fire

Sage of fire from Zelda.

Fire rage

A fiery fury that increases fire damage starting at 1d4 at level 3, when you are raging increasing to 1d6 at level 4 and by an additional d6 every to levels above.

Flaming weapon.

3 times per long rest you create a weapon of your choice out of magma this weapon deals d4 fire damage two bludgeoning damage. This targets movement speed is halved, and you expend one of the charges of flaming weapon to force the target to roll a dc 10 constitution saving throw or have a point of exhaustion.

 

Magma pit

Twice per long rest you can open a pool of lava with a 15-foot radius, anyone in the radius must succeed on a dc15 dexterity saving throw or be restrained and 5 take 1d8 fire damage on the end of its turns. The save can be repeated at the beginning of the creature's turns but instead is a strength save. 

Volcanic fury

 

Level 14 volcanic fury When you expend all charges of rage at once you gain a fiery form that allows all of your fire damage dealt to be increased by 1d12 + 1d6 for every barbarian level above 12 but if you fail a dc 15 wisdom save when you rage you see all creatures as hostile this save is repeated at the end of all of your turns.