Great Worm

Chitonous Visage

Starting at 1st level, you can shift into your Chitonous Visage, calling upon the creature that holds your soul; you grow your monstrous visage, chitonous skin, and chittering long teeth. Using your action to turn into your Chitonous Visage, every enemy within 30 ft must make an Intelligence Saving Throw or be frightened of you until the end of their next turn. If they fail the saving throw by more than 5, they are paralyzed until the end of your next turn. Your AC is increased passively by your Charisma Modifier. You cannot speak; you can screech and make sounds, but this doesn't affect your spell casting. In this form, all Charisma (persuasion) and Charisma (performance) skills are at disadvantage while you are within your Chitonous Visage. You gain Websense and Webwalk.

You can do this as many times as your proficiency bonus, and a short or long rest revitalizes all expended uses. 

Expanded Spell List

A Great Ancient Worm blesses you with an expanded list of spells. The following spells are added to the warlock spell list for you.

The Great Worm Expanded Spells

Sharp Skin

Starting at 6th level, you call upon the desert sharp teeth and worming power of your ancient patron. Whenever you make an attack roll through magic or a physical attack with a weapon, you can expend a use of your Chitonous Visage, initiating it as a bonus action next round and making the attack an advantage. In doing so, you develop chitonous skin; you gain resistance to piercing and slashing damage while under your Chitonous Visage. 

You passively gain tremorsense for 60 feet and a burrowing speed of 45 feet. 

Sand Wreathing

Starting at 10th level, you can summon a flowing torrent of orbiting sand, dust, or some other fine particulate; it flows around you and makes you hard to see, and images of you fly off of you as you move. As a bonus action, you can start Sand Wreathing, which lasts a minute or until you dismiss it. While it is initiated, you are under the effect of the Blur spell and the Mirror Image spell. 

Ceasless Squirming

Starting at 10th level, you have taken your soul and wrapped it in the forever squirming of a great worm, or maybe its children, you gain immunity to exhaustion.

Summon Sibling

Starting at 14th level, you can summon one of the children of the great worm or maybe a ghostly incarnation of your patron, a fellow sibling of your soul. You can summon a young purple worm to your aid; this creature is an ally; you can communicate with it through telepathy and the screeching speech of your Chitonous Visage. It will last 6 hours or until dismissed. 

The number of times allowed summoned is determined by your Charisma modifier, resetting every long rest. You can only deploy a number of siblings at the same time equal to your level, subtract 10, and divide by 3, rounding down.