The Unformed

Before there was space, before there was form, matter, soul or magic, before time itself began, the universe was a singularity. Everything and nothing, nowhere and everywhere, truly and completely unformed. When time began, there were born from the chaos a number of beings which each took on an aspect of this new universe. But a piece remained behind, refusing to take definite form or aspect. This piece of the primal chaos lives on today as the Unformed. Its voice can be heard by those who resist the bonds placed upon them, by those who remain true to themselves. It cares for this flock, as much as something like that can care. They are parts of the same whole, after all.

Minor Change

Starting at 1st level, you learn the Thaumaturgy and Primal Savagery cantrips. They count as warlock cantrips for you, but they don't count against your number of cantrips known.

Reform

Starting at 6th level, you can shift into an echo of any creature of CR 1/2 or below, including sapient races. Echoes are imitations, so they gain the creature's physical attributes - strength, dexterity and constitution scores, as well as movement and physical actions(e.g. bite, claw) but not their senses, magical properties, or special abilities. Echoes aren't perfect, and a creature who inspects one may make a perception or investigation check opposing your deception to determine that it is not the real thing. You are able to use this feature once per short rest.

Unbent Path

Starting at 10th level, you are immune to being charmed, have resistance against psychic damage, and have advantage on saving throws against being deceived or persuaded.

Boundless Form

Starting at 14th level, you've gained mastery over reforming. You can shift into echoes of CR 2 and below, and your echoes are almost indistinguishable from the real thing. You have advantage of deception checks to pass yourself off as the real creature. You are now able to shift a number of times equal to 1/4 of your warlock level, rounded down. You regain all uses on a short rest.

Expanded spell list

1st Disguise Self, Command

2nd Alter Self, Blur

3rd Nondetection, Blink

4th Polymorph, Fabricate

5th Awaken