Path of Disaster

(A finished and adapted version of Mike Mearls subclass)

Unlike other barbarians, those that follow this path are truly unique. The elemental warrior's rage manifests as an unstoppable force of nature, to be feared and respected by allies and enemies alike. With the body and will of a warrior and the equal fury of both disasters and of the elements are unleashed.

Avatar of Disaster

Starting at 3rd level, when you rage you undergo a startling transformation. You may choose from the following options when you rage. You can only benefit from one disaster at a time, though if you drop your rage and enter a new one, you may choose another disaster.

• Volcano. You transform into a creature of obsidian and fire. Your rage bonus damage is fire damage. Your rage bonus damage is doubled when using Reckless Attack.
• Vortex. You transform into a creature of lightning and wind. Your rage bonus damage is lightning damage and your speed increases by 10ft. When you hit a creature with your Reckless Attack, it has its speed reduced by half until the end of your next turn. 
• Earthquake. You transform into a creature made of earth and stone. The first time you hit a creature with your Reckless Attack you gain a bonus to your AC equal to your rage damage bonus until the start of your next turn. 
• Tsunami. You transform into a creature of coral and seawater. You can move through anyone’s space but can't end your turn in another creature's space. When you hit an enemy that is Huge or smaller with your Reckless Attack you can push them back 5ft.

Mobile Calamity

At 6th level, you gain the ability to better manoeuvre in your environment. While you are raging you gain the following benefits based on the disaster you choose when you enter your rage.

• Volcano. Your jump distance is doubled and you gain resistance to fire damage.
• Vortex. You no longer take falling damage.
• Earthquake. You are no longer affected by difficult terrain.
• Tsunami. You can now breathe underwater and gain a swim speed of 50ft. 

Elemental Soul

Starting at 10th level, for 1 hour you can channel the essence of a disaster to alter your physical form. You retain all of your stats while in this form though any equipment you have disappears into your form until you change back. You cannot attack whilst in any of these forms. You can use this ability a number of times equal to your proficiency modifier and regain all uses at the end of a long rest.

• Volcano. Your body turns to molten rock with lava seeping from your pores. In this form, you are immune to fire and can swim through lava. You shed bright light within 10ft. and dim light for a further 10ft.
• Vortex. Your body shifts into a wind form that resembles a tornado. You gain a flying speed equal to your walking speed and gain resistance to thunder and lightning damage. 
• Earthquake. Your body is covered in rock and soil. You gain a +4 bonus to your AC. You can burrow underground and gain a burrow speed of 50ft. 
• Tsunami. Your body turns translucent and is made of water. You can move through other creatures spaces but cannot start your turn there. Whenever you move, you do not provoke opportunity attacks. If you use this feature in the water you can turn into a giant wave strong enough to carry a ship along the water.

Catastrophic Overload

Starting at 14th level, whilst you are raging you can choose to channel all your focus into your elemental powers, causing a temporary overload. You can only gain the benefits of one of the following, based on what disaster you entered your rage with and at the end of your turn you take damage equal to your level that can't be reduced in any way. You can use this feature a number of times equal to your proficiency modifier and regain all uses at the end of a long rest.

• Volcano. You can cause your rage bonus damage to triple instead of double when using your Reckless Attack. This benefit lasts until the start of your next turn.
• Vortex. You can cause your Reckless Attacks to instead reduce the creature's speed to 0, instead of being halved, and your speed increases by 20ft. instead of 10ft. This benefit lasts until the start of your next turn.
• Earthquake. You can cause the Reckless Attacks you hit with to knock the creature prone. The creature must make a Strength saving throw against a DC that equals 8 + your Proficiency + your strength modifier. This benefit lasts until the start of your next turn.
• Tsunami. Whenever you hit a creature whilst using your Reckless Attack feature, you can push it back 10ft. instead of 5ft. If this movement should move the creature against a vertical surface, it slams into it, causing it to take bludgeoning damage equal to your Strength modifier.