The Subterranean

The Subterranean is a prisoner of their own design. At first, they chose willingly to move beneath the land, but now they are trapped for as long as the earth remains. Dwelling underneath the soil, they are responsible for almost every natural disaster. The Subterranean is trying to get out of thier prison, but is unable to do it by themselves so they seek out sympathetic creatures willing to help them. They lurk now in the deepest layers of the Underdark, isolated by thick walls of dirt and stone. The Subterranean can be any entity that is trapped underneath the ground. 

Expanded Spell List

The Subterranean lets you choose from an expanded list of spells when you learn a warlock spell. The following spells are added to the warlock spell list for you.

Fiend Expanded Spells

Spell Level	Spells
1st	earth tremor, feather fall
2nd	maximilian's earthen grasp, dust devil
3rd	erupting earth, meld into stone
4th	stoneskin, conjure minor elementals
5th	transmute rock, passwall

Earthen Encasing

Starting at 1st level, you can control the earth to cover creatures in stone. As an action, you can choose to encase a medium or smaller creature with stone. You can choose any one creature or yourself as long as they are touching the ground. If they fail a dexterity daving throw, they are encased. Creatures can choose to willingly fail the save. While encased, a creature is in complete darkness. Also, they cannot target other creatures or make attacks on things other than the stone encasing it self. The stone encasing has hitpoints equal to twice your Spell Save DC. You can choose to end this encasing as a free action. This feature can be used a number of times equal to your charimsa modifier and recharges on a long rest.

Stone Clutch

Starting at 6th level, you can call on your patron to protect you from strikes. When a melee weapon attack would normally hit you, you can use your reaction to form a stone arm and seize their weapon. If they fail a strength saving throw, you can grab their weapon. A creature can try to grab the weapon back and make another strength saving throw as an action. You can use this feature once per short rest.

Minor Petrification

Starting at 10th level, your body begins to transfrom to rock. You gain immunity to the petrified. Also, you gain immunity to the poisoned and resistance to poison damage. 

Petrifying Grasp

Starting at 14th level, when you cast a spell at a single creature, you can force them to make a constitution saving throw. On a failed save, they are petrified for 1 minute. They can repeat this saving throw at the end of their turn. Creatures can choose to willingly fail the save.