You have forged a pact with an enigmatic being, who has varying names across the multiverse, such as [REDACTED], The Mystery Man and the most common, which is the Man Who Speaks in Hands. To those who learn of him, however, they refer to him as Dr. W.D. Gaster. He has a dark and murky history, and the story is slightly altered whenever it is passed by mouth to mouth, but the basic knowledge is this:

Once, Dr. Gaster was an extraordinary scientist, but one day, an experiment went wrong, and he fell into his creation. The shards of his splintered soul landed in every universe, and that shard is what you draw your power from by having him as your patron.

Expanded Spell List

Gaster 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.

The Man Who Speaks In Hands Expanded Spells

Spell Level	Spells
1st	Tasha's hideous laughter, command
2nd	phantasmal force, alter self
3rd	animate dead, bestow curse
4th	arcane eye, greater invisibility
5th	legend lore, Bigby's hand

Gaster Blaster

Starting at 1st level, Gaster grants you access to one of his first inventions, the Gaster Blaster. It resembles a sleek, canine like skull with which you can use to cast the eldritch blast cantrip a number of times equal to your proficiency bonus. Once you have used it up to its maximum you can reuse it again after a short rest.

Gaster Follower

Gaster marks his followers so that when his all-seeing eye sweeps across the multiverse, he can identify those loyal. Your body and anything you wear or hold becomes grey and monotone, which is seen as a bad omen within superstitious people, causing people to be naturally afraid or cautious around you.

Additionally you can speak, read and write a language called WingDings. It is a language consisting of symbols and when spoken it sounds like a garbage noise that only other Gaster Followers can understand. 

Skeletal Appearance

You are slowly warped into Gasters image. Your skin begins to cling closer to your bones and also now appears white instead of grey, leading to you resembling a skeleton. You also are now resistant to necrotic damage.

Very, Very Interesting

Starting at 10th level, you gain insights of Gaster's infinite cosmological wisdom of the multiverse, both from his field of study and the horrors he witnessed after his ascension. You have advantage on all Intelligence (Arcana) and Intelligence (History) checks.

Egg

At 14th level, Gaster feels that you have been most devout and are in need of an offering. In a dream during along rest you are given an Egg by your master. As an action you can 'use' the Egg by presenting it. Roll a d100. On anything other then a 66, nothing happens. On a 66 the Egg cracks open and releases a shard of [REDACTED]. Everyone within 30 feet is slain instantly and their soul is spread in splinters across the multiverse. Creatures who die in this way cannot be returned to life aside divine intervention. You are also killed, in the same way that killed your patron, a most fitting death.