Path of the Exarch of Enthusiasm

 The Exarch of Enthusiasm is a sort of first place trophy for the mortal creature with the greatest ability to continue against all odds. It grants the bearer effectively endless energy but little to no actual additional strength with which to use that energy, and it can be wrested away by falling short of it's expectations and another mortal more resilient than you existing. This subclass is designed for the current bearer of that power, Meinir Delwyn Aerfen, but it may be used by any barbarian who wishes to empower their attacks with lightning-themed abilities on any world.

Energetic Attacks

Starting when you choose this path at 3rd level, you can channel raw energy into your weapon strikes. While you’re raging, the first creature you hit on each of your turns with a weapon attack takes extra damage equal to 1d6 + half your barbarian level. The extra damage is Lightning or Thunder damage, chosen before you make the attack roll.

Rush of Excitement

Starting at level 3, when you use your battle rage, your enthusiasm cannot be contained as the joy of being alive to have this fight overwhelms you. The Exarch fill your body with an overwhelming amoun of energy. You gain resistance to Thunder and Lightning damage, and you gain the ability to Dash as a bonus action while Raging.

You lose the benefits of this feature if you are not in control of your own actions.

Surge Step

Starting at 6th level, your built-up energy can be wielded to hurtle you through battlefields.While Raging, you may travel exactly 30ft in a straight line as a Bonus Action, dealing 2d6 Lightning damage to all creatures and objects in a straight line between your starting point and destination. Affected creatures may take only half the damage with a successful Dexterity Saving Throw, with a DC of 8 + your proficiency modifier + your Dexterity score. You can use this ability only once per rage. If your destination is not on a surface you can stand on, you immediately begin falling after your Surge Step.

Inclement Weather

 At 10th level, your wells of contained fury and excitement can overflow your vessel and escape into the battle of it's own accord. Once per Long Rest, when you rage you may surround yourself in a crackling field of energy that extends 10ft in all directions that lasts until your rage ends and moves with you. Creatures other than you within this area are Vulnerable to Lightning and Thunder damage.

If you Surge Step while the Inclement Weather persists, the Lightning damage you deal extends to any creatures within 10ft of the path you travel, and these creatures are vulnerable to that Lightning damage.

Stormborn

Beginning at 14th level, your ability to crash through the fray has burst it's banks like a flooding river, and only death will stop you from having the time of your life. You may Surge Step every turn while affected by Inclement Weather. Additionally, whether or not you are affected by Inclement Weather at the moment, you gain the following benefits:

• The lightning/thunder damage from your Energetic Attacks feature will extend to another creature within 15ft of the original target
• When you Surge Step, all creatures within 15ft of your destination point may roll a Constitution saving throw with a DC equal to 8 + your proficiency modifier + your Strength modifier. If they fail, creatures take 4d8 Thunder damage, which is haved on a successful save.
• Your movement speed cannot be reduced by any means, magical or otherwise, unless your movement speed would be reduced to zero by a single effect (including conditions such as Stunned/Restrained, and the drawback of being targetted by Haste)