Treading the lines between two states, the Storm Titan is at once both the calm, inner eye and the furious wind, thunder & lightning that surrounds it.
Your inner eye is constantly observing & aware of the world around you, even as your furious strikes drive the strength of the storm into your enemies. Wisdom informs your choices, allowing you additional attack opportunities, and allowing you to discharge storm energy into your opponents.
Your rage is no longer a mindless fury, but instead acts like a storm, bridging two unique but coexisting states: the calm, inner eye that rapidly observes your surroundings, yourself and your actions, and the fury of the winds that drives your actions with deadly force.
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. You can have at most 20 Storm Charges at any one time. Any charges that you might gain over the cap of 20 are instead discarded.
Fury: You can spend 1 Storm Charge to make an additional melee attack as a bonus action.
Calm: On a turn where your Rage would otherwise end, you can choose to spend 1 Storm Charge to maintain it instead. If you spend a Storm Charge on another ability during this turn, your Rage is automatically maintained. When your Rage ends, all remaining Storm Charges have a cumulative 10% chance to restore usage of Rage.
You gain additional ways to use Storm Charges at later levels.
Fury: On a successful melee attack, you can spend Storm Charges (up to your Wisdom modifier) to deal 1d6 additional thunder damage.
This damage increases as you gain Barbarian levels: at 6th level, 1d8; at 10th level, 1d10; at 14th level, 1d12.
Calm: Your inner eye observes the openings and weaknesses you make while performing Reckless Attacks. Creatures who take advantage against you subtract half your Wisdom modifier from their rolls.
You gain the option to use your Wisdom modifier in place of your Dexterity modifier when calculating your armor class for the purposes of unarmored defense.
The storm inside you grows in strength. Storm Charges now deal 1d8 thunder damage.
In addition, any time an enemy attacks you successfully while raging, they take thunder damage equal to your Rage bonus.
Fury: The ocean crashes and swells as the storm above stirs it with great winds. While raging, the power of these gusts bolster your abilities and the distance you can jump is increased by your Wisdom and Constitution modifiers. Additionally, you no longer require a running start to travel your full jump distance and you have advantage on any saving throw triggered by jumping, as well as any non-Strength ability check also related to jumping.
You may also spend Storm Charges (up to your Wisdom modifier) to increase your jump distance a further number of feet equal to your Strength modifier.
Calm: Your inner peace protects your mind from mental dangers. Danger Sense now applies to saving throws against charms & fear.
While charmed or frightened, you can use an action to spend 2 Storm Charges and immediately end the effect. This counts as an attack for the purposes of maintaining rage.
The storm inside of you is so strong it threatens to spill out of you. Storm Charges now deal 1d10 lightning damage.
You gain resistance to lightning and thunder damage.
Fury: You no longer trigger opportunity attacks if you move away by jumping. In addition, you can use your bonus action to spend 2 Storm Charges and take the Dash action.
After jumping into combat range with a creature, your next successful melee attack against them deals additional thunder damage equivalent to a Storm Charge, without expending one. You can only trigger this damage once per turn.
Calm: As a reaction, you can spend a number of Storm Charges (up to your Wisdom modifier) to increase your AC by that amount when hit. This increase lasts until the end of your next turn, and also applies to the triggering attack.
As a bonus action on your turn, you can spend 2 Storm Charges to take the Dodge action.
The storm inside you is at its peak. While raging, faint clouds can be seen swirling around you, and metallic objects that you touch may spark with lightning. Storm Charges now deal 1d12 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). At the end of a turn, you can choose any creature that you have moved through and cause them to suffer thunder damage equivalent to your Rage bonus.
Fury: The strength of the storm within you is unstoppable. Even in the darkest cave or under a cloudless sky, you can extend tendrils of it to affect the world. While raging, as an action on your turn, choose a number of Storm Charges to deal as damage and a number creatures up to double your Wisdom modifier (a minimum of 1) within 45ft.
Each creature must make a Dexterity saving throw or suffer lightning damage equal to the number of Storm Charges spent. On a save, they suffer half as much damage.
Calm: Though the storm within you is now at full strength, your inner eye remains calm. Your Initiative bonus now includes your Wisdom modifier.
When you roll initiative for combat and you have no uses of Rage left, you gain 1 usage of Rage. This weakens the storm slightly, and you must subtract 2 from the number of Storm Charges that you gain when you next Rage before you complete a long rest.