Shake the foundations of the world

Given your ancestry as a mountain spirit, you have the ability to cause a massive earthquake centred on where you stand, shaking the ground to its foundations. To do so you must make yourself so emotional and unstable that you fail a CON 10 save, you can do this with disadvantage IF you meet any of the following:

• Are below 1/2 HP
• Are emotionally distraught
• Are angered beyond usual
• Have a companion who succeeds on an intimidation 14 check and destabilizes you with personal knowledge

Once cast, the ground begins to shake as you evaporate into a haze, wispy tendrils streaming off from you like you are unravelling, while screaming ever louder until it becomes inaudible, eventually losing control of your self and reverting to an elemental existence as the world around your former place shakes and splits with violent crashes.

Recovery:

Once cast, you must make three death saves or be stuck as an unravelled elemental spirit in an INCORPOREAL form, floating directionless in the twilight of this world, your gear and clothes (IF they survive) remain where you were standing.

Incorporeal

Resistances: bludgeoning, piercing and slashing damage from non-magical weapons

Spell casting: You are only able to cast cantrips which do not require physical components, unless you are able to hold said components at the time. You are also immune to all spells being cast on you unless they cause force damage.

Incorporeal Movement: You can move through other creatures and solid objects as difficult terrain. If you end your turn inside a solid object you take 1d10 force damage.

Ethereal Overlap: You can see and interact with creatures on the ethereal plane, and they can see and interact with you.

Limited Interaction: You deal half damage to targets that are neither incorporeal nor ethereal. You can manipulate objects on the material plane, but to do so you must make a dis-STR check equal to 8x its weigh.

Speaking across planes: You can speak to corporeal beings, but must make a persuasion check beating their INT score, you do not have disadvantage on this.

Etherial Traits: You don't need to eat, drink, breathe or sleep. When you reach 0 hit points, your form dissipates into a mist are lost forever.

Possession (3 charges): You can attempt to take possession of another creature's body by jumping into them and overpowering their own control, the creature must make succeed on a DC 13 Charisma saving throw or be possessed for 2 hours, after which the target is incapacitated for an hour and loses control of its body. You now control the body, but you do not deprive the target of awareness. You use the possessed target's statistics, but don't gain access to the target's knowledge, class features, or proficiencies.

Return: It is possible to return to a material state, but how this is to be done, is unknown...