Path of embers

Fire is a force of nature. Despite what many attempt throughout their lives whether through bargains with unknowable creatures or magic, fire is very hard to tame. By its very nature, fire is chaotic, dangerous and unpredictable. Lighting a fire on the battlefield is just as likely to wipe you and your troops out as it is to harm your enemies. By following the path of embers, you have come to realise that fire is not meant to be restricted or captured to be used properly. It must be simply directed towards the enemy and left to do what it does best; destroy.

Now, though, you have the same capability for destruction. Let the raging inferno inside you cause untold anarchy, and revel in the pyre you have built for all.

Cruel Flare

Starting at 3rd level when you choose this subclass, your
strikes begin to burst into a glorious display of flame
Whenever you hit a creature with a weapon attack while
raging, it takes an additional 1d4 fire damage.
The damage increases to 2d4 at 6th level 3d4 at 10th
level and 4d4 at 14th level
In addition, you become resistant to fire damage while
raging.
Finally, when you use your Reckless Attack feature, the
next weapon attack you make before the end of your next
turn deals extra fire damage equal to twice your Rage
Damage bonus.

Pyre Starter

Starting at 3rd level, you can use your action to touch a
flammable object that fits within a 5 foot cube or smaller
that isn't being worn or carried (such as a pile of wood or a
bale of hay) and cause it to ignite. At 10th level, you can
ignite objects that fit within a 10 foot cube or smaller.

Armour of ignition

At 6th level, you can channel your fury into a protective
force, scorching all who approach you.
While raging, you can use a bonus action to channel your
internal flames. If you do so, your AC increases by 2 and
hostile creatures take fire damage equal to your
Constitution modifier (a minimum of 1) if they enter within
10 feet of you or start their turn there. This ability lasts
until your rage ends.
When your rage ends, make a Constitution saving throw,
gaining 1 level of exhaustion on a failed save. The DC of
this saving throw is equal to 10 + the number of rounds
your rage lasted.

Eternal Sun

Starting at 10th level you gain the following effects:
If you are within 5 feet of a fire that is the same size as
you or larger and there is another fire within 30 feet of
you, you can use a bonus action and spend 5 feet of
movement to teleport to a space within 5 feet of either
fire.
You become immune to the effects of extreme heat, as
described in the Dungeon Master's Guide.
You become immune to fire damage while raging.

Inferno plume

Starting at 14th level your flames can raze the paths you
tread
When you start your turn, you can choose to double your
walking speed, setting the spaces you enter on fire as you
enter them A creature that enters a space set aflame in
this way must make a Dexterity saving throw (DC=8+
Proficiency bonus + Constitution modifier), taking 3d1 2 fire
damage on a failed save and half that on a successful save
The fire dies down at the end of your next turn.
You can use this ability a number of times equal to your
Constitution modifier (a minimum of once), regaining all
expended uses upon finishing a long rest.
In addition, Whenever you deal fire damage to a creature
while raging, you ignore resistance to that fire damage and
treat immunity as resistance to that damage.