Barbarians who follow this path have learned to tap into the forces of Dunamancy, letting them augment the force of of their swings with the power of gravity and crush those who cannot withstand its power with their mere presence.

Dunamanc Rage

Starting at 3rd level, you can harness the forces of gravity and Dunamancy to alter the gravity around you while raging.

As part of the bonus action to activate your rage, you can increase the gravity in a 10-foot cube for the duration of your rage. The following effects are applied to creatures other than yourself that enter the aura.

• The area around you counts as difficult terrain.
• The weight of everything doubles and jump heights are halved
• The DC of Strength saves and Athletics checks increases by an amount equal to your strength modifier within the area.

The size of this cube increases to 30ft at 10th level

Gravity hammer

Beginning at 6th level,  you can briefly intensify the earth's pull on creatures you hit with your attacks. 

Whenever you hit a creature with a attack while raging, you can spend an number of  hit dice up to your strength modifier to cause a meteoric impact to spread out from the point of contact.

The impact of this shakes the ground in a 10-foot radius. Each creature other than you must make a Dexterity saving throw. On a failed save, a creature is knocked prone and takes bludgeoning damage equal to a roll of the expended Hit dice+your strength modifier. On a successful save, the creature takes half as much damage (rounded up) and is not knocked prone. 

At 18th level, you improve the effects of your gravity hammer. If a creature fails its save, it is stunned for 1 round, knocked prone, and takes damage equal to twice the amount of damage rolled + your Strength modifier. On a successful save, the creature takes half as much damage and is not knocked prone or stunned.

The save for this is equal to 10 + your Strength Modifier + your Constitution Modifier

Crushing Presence

Beginning at 10th level, You can focus the earth's pull on a creatures around you, holding them in place to keep them from moving. As an action, you choose up to 6 creatures within 100 feet of you. These creatures must make a Strength saving throw. On a failed save, its speed is becomes 0 and they are knocked prone as long as it is within 100 feet of you. The target must make another Constitution saving throw at the end of each of its turns. On a successful save, this effect ends.

The save for this is 10 +  your strength modifier + your Constitution modifier

Raging Singularity

Starting at 14th level, when you enter a rage, you can chose to have gravity in a 80-foot-radius, 100-foot tall cylinder centered on yourself be thrown into chaos and all creatures and objects that aren’t somehow anchored to the ground in the area begin to fall towards the top of the cylinder and orbit around you.

A creature can make a Dexterity saving throw (DC 12 + Strength Mod + Con Mod) to grab onto a fixed object it can reach, thus avoiding the fall. Creatures that are flying or not on solid ground have disadvantage on the saving throw and creatures with some kind of climbing ability (like a spider climb spell or a climbing speed) have advantage

If some solid object (such as a ceiling) is encountered in this fall, falling objects and creatures strike it just as they would during a normal fall. If an object or creature reaches the top of the area without striking anything, it remains there, swirling in a rapid orbit for the duration of your rage.

For each round you are raging, creatures caught in it take bludgeoning damage equal to double your strength modifier at the start of their turn (presumably from being smacked around by all the objects thrust into the air by your rage) and their movement speed is reduced to zero if they don't have a fly speed or are on a solid surface (like a ceiling)

At the end of your rage, affected objects and creatures fall back to the ground and take falling damage as normal upon colliding with it.