The Gelatinous Convocation

You’ve made a pact with the cheerful wandering cubes of sentient ooze that wiggle and wobble their way across the multiverse to visit worlds beyond measure with the singular goal of spreading their offspring within the deepest dungeons to collect and absorb the memories of the fallen. As they happily bounce between the planes, they occasionally encounter a soul they view as truly amusing, so they offer a measure of their strange power over the slimes and oozes of the world using the magic that they wield with a mere wave of their pseudopods.

Caustic Blast

Whenever you cast a cantrip that deals damage or make a weapon attack, you can use a bonus action to infuse it with acidic energy. The cantrip or attack deals acid damage instead of the normal type, can target objects, and inflicts twice as much damage to unattended objects and structures. If a creature damaged by this acid is using a non magical shield,they must make a Dexterity saving throw against your warlock spell save DC. If they fail, their shield is destroyed.

Acidic Body

At 10th level, your form is infused with a caustic power. You gain immunity to acid damage. Whenever a creature starts its turn while involved in a grapple with you, you can choose to have it suffer 2d8 acid damage. 

Consuming Joy

At 14th level, you fully understand the happiness of the Gelatinous Convocation, granting you immunity to the charmed condition. You can cast polymorph using a warlock spell slot, but you can only turn the target into an ooze instead of a beast. You can cast this spell once without expending a spell slot, and this use recovers when you finish a long rest.

Expanded Spell List

The Gelatinous Convocation 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.

Expanded Spells

SPELL LEVEL	SPELLS
1st	grease, hideous laughter
2nd	acid arrow, enlarge/reduce
3rd	meld into stone, water walk
4th	fire shield, stone shape
5th	cloudkill, hallow

Recovered Memories

At 1st level, you learn to dissolve the bodies of the dead and learn from their lives. As an action while standing adjacent to a corpse, you can produce an iridescent acid that consumes the corpse over the course of one minute. After the minute has passed, you can collect the acid to gain the memories of the creature from the last 48 hours of the creature’s life, as well as the most important memories within their final year. You can produce this acid once, and this use recovers whenever you finish a long rest.

Cheerful Friend

Also at 1st level, you can speak with oozes and communicate simple concepts, even if they cannot speak a language. You are not subject to acid damage that would be caused by a non-hostile ooze touching you, and you gain resistance to acid damage.

Catalog of Experience

Whenever you use your Recovered Memories feature to absorb the knowledge of a creature, you can store the experience in your Book of Shadows, and make it come to life upon the pages of the book.You can copy and transfer any memories within your Book to another creature by touching them with the Book as an action.

Great Divide

At 6th level, your body becomes somewhat... slimy. Whenever you suffer damage, you can use your reaction to divide into a Medium swarm of Tiny oozes. Your hit points remain the same, and you function as a single unified swarm that occupies the same space as a Medium creature. While in this state, you cannot take actions other than the Dash action, your movement speed is halved, you gain resistance to bludgeoning, piercing, and slashing damage, you gain immunity to acid and poison damage, you don’t provoke opportunity attacks, and you can move through any space as narrow as 1 inch without squeezing. You can choose to return to your normal form without using an action whenever you wish, provided there is room to do so. You can use this feature once, and this use recovers whenever you finish a short or long rest. When you reach 10th level, you can use this feature at will as an action, but you can still activate this feature as a reaction only once.