Path of Precognitive Resonance

Channel precognitive flashes to fuel your rage.

Barbarians who follow the Path of Precognitive Resonance breach the fabric of time through the primal power of their rage. They gain flashes of the future and use this ability to give themselves a more tactical advantage over their enemies in battle.

Resonant Rage

Starting when you choose this subclass at 3rd level, your Rage allows you to quickly jump through time itself. While your Rage is active, and as long as your Speed is greater than 0, you can teleport up to 15 feet once on your turn to an unoccupied space you can see (no action required). If you do so, you have advantage on the next melee attack roll you make this turn. You can choose to forgo the advantage granted by this feature to instead impose disadvantage on the next attack roll made against you before the start of your next turn.
The distance you can teleport using this feature increases as you reach higher Barbarian levels. Starting at 6th level, the distance you can teleport increases by 5 feet. You gain this increase again when you reach 10th level, and again at 14th level.

Primal Precognition

Beginning at 6th level, whenever an effect forces you to make a saving throw while your Rage is active, you can use a Reaction to give yourself advantage on the save. If you do so, you gain a bonus to that saving throw equal to your Rage Damage bonus. If you succeed on the saving throw, you can then teleport up to 10 feet to an unoccupied space you can see as part of that same reaction.

Improved Danger Sense

Starting at 10th level, your precognitive abilities allow you to sense danger even faster than your already heightened instincts, allowing you to warn your allies of incoming trouble before it strikes. Creatures of your choice that are within 15 feet of you have advantage on Dexterity saving throws unless they have the Incapacitated condition. A creature must be able to hear or see you to benefit from this feature.
Additionally, when you or another creature benefitting from this feature succeed on a Dexterity saving throw to take half damage from an effect, you each instead take no damage. 

Resonance Echo

Beginning at 14th level, when you teleport using your Resonant Rage ability, you can choose to leave behind an echo of yourself in the place you left. The echo retains all of your statistics, conditions and characteristics, but it is intangible and cannot take any Actions, Bonus Actions, movement, or Reactions. Until the end of your turn, you can use a Bonus Action to teleport back to the echo's position. When you do so, any changes to your hit points, armor class, conditions, or any of your game statistics that have occured since you created the echo are erased, and you assume the same statistics and conditions as the echo. You cannot regain any expended Actions, Bonus Actions, movement or Reactions in this way. The echo disappears at the end of the turn in which it was created.
You can use this feature a number of times equal to your Constitution modifier, and you regain all expended uses when you finish a Long Rest.