Rage of the Storm Titan (3rd level)
Your rage is no longer a mindless fury, but instead acts much like a storm, bridging two unique but coexisting states: the calm, inner eye that rapidly observes and catalogues, and the fury of the outer winds that drive you into action.
When you begin your rage, you gain Storm Charges equal to your Wisdom modifier plus your proficiency bonus. On subsequent turns you can spend a usage of Rage to gain additional charges. On a turn where your Rage would otherwise end, you can choose to spend one of these Storm Charges to maintain it instead. When your Rage ends, all unused Storm Charges have a cumulate 10% chance to restorea usage of Rage.
As a bonus action, you can spend a Storm Charges to make an additional melee attack as a bonus action. You can only use this ability if you took the Attack action on this turn.
You gain additional ways to use Storm Charges at later levels.
The Furious Typhoon (3rd level)
You can spend Storm Charges to deal additional damage to a target that you have successfully attacked, deciding after the roll is determined. Each Storm Charge deals 1d6 lightning or thunder damage (your choice) damage: this damage increases as you gain Barbarian levels.
The Storm-Shield (3rd level)
During your rage, your internal eye rapidly observes and catalogues every opening you leave. When you invoke Reckless Attack, all subsequent attacks made against you that benefit from advantage must subtract your Wisdom modifier from the total.
When calculating your Unarmored Defense, you can use your Wisdom modifier instead of your Dexterity modifier.
Darkening Clouds (6th level)
The storm that fuels your fury grows. Storm Charges now deal 1d8 lightning or thunder damage.
In addition, any time an enemy attacks you successfully while raging, they take lightning or thunder damage equal to your Rage bonus.
Crashing Seas (6th level)
The winds of great storms over oceans cause the waves to swell and thrash about. The power of these waves bolster your abilities, and the distance you can jump is doubled. You no longer require a running start to travel the full distance, and you have advantage on any saving throws or ability checks related to this movement.
Peaceful Core (6th level)
Your inner peace protects your mind from mental dangers. Danger Sense now applies to Wisdom saving throws against charms & fear.
While charmed or frightened, you can use an action to spend 2 Storm Charges and immediately end the effect.
Gathering Storm (10th level)
The storm inside you grows even stronger. Storm Charges now deal 1d10 lightning or thunder damage.
You gain resistance to lightning and thunder damage.
Leaping Waves (10th level)
You no longer trigger opportunity attacks if you move by jumping. In addition, you can use your bonus action to spend a Storm Charge and take the Dash action.
After jumping into combat range with a creature, your next successful melee attack against them deals additional damage equivalent to a Storm Charge (your choice of lightning or thunder), without expending a Storm Charge. You can only trigger this damage once per turn.
Shield of Storms (10th level)
As a reaction when you are struck by a melee attack, you can spend a Storm Charge to increase your AC by 3 until the end of your next turn.
As a bonus action on your turn, you can spend 2 Storm Charges to take the Dodge action.
Pinnacle (14th level)
The storm inside you is almost at its peak. Storm Charges now deal 1d12 lightning or thunder damage.
While raging, you now ignore difficult terrain and can move through creatures, although you cannot end your turn in a creature's space. You can choose any creatue that you move through and cause them to suffer lightning or thunder damage equivalent to your Rage bonus.
Lightning Storm (14th level)
Even in the darkest cave or under a cloudless sky, you can extend tendrils of the storm within you. As an action on your turn, choose a number of Storm Charges and creatures up to your Wisdom modifier (a minimum of 1) within 30ft.
Each creature must make a Dexterity saving throw. On a failure, they suffer lightning damage equal to the the number of Storm Charges spent, or half as much on a success.
The Darkened Eye (14th level)
You can add your Wisdom modifier to your Initiative roll.
If you roll initiative and have no uses of Rage left, you gain a use of Rage. However, you only gain half the number of Storm Charges when activating this rage.