As an action, you can polymorph into a small or medium creature, or revert to your true form. If hit by an attack that causes fire or cold damage you revert back to your true form, dropping all equipped gear (except magical items) on the ground.

You can’t duplicate the appearance of a creature you’ve never devoured, and you revert to your natural form if you die. While in this form you lose access to all Ooze Form and Liquid Form Traits and Abilities aside from Shapechanger.

You decide what you look like, including your height, weight, facial features, the sound of your voice, coloration, hair length, sex, and any other distinguishing characteristics. You can make yourself appear as a member of another race, although it must be a creature of small or medium size. All of your statistics change to match the creatures except for your Intelligence and Charisma.

While in this form you may use the natural attacks of the creature whose form you are using (for example if you are a cat you can attack using your claws, or your teeth as dog. You cannot use Multiattacks), however you may not use any magical, supernatural or elemental attacks the creature had. (just because you took the form of a dragonborn does not mean you have the ability to use a breath attack.) In this form you may also equip non magical gear.

Even to the most astute observers, your ruse is usually indiscernible. If you rouse suspicion, or if a wary creature suspects something is amiss, you have advantage on any Charisma (Deception) check you make to avoid detection.

In addition, if you fail your saving throw while in a zone of truth, you immediately revert to your true form.

An Ooze is made up of Acidic fluids that allow them to devour almost anything they touch. This comes with both benefits and drawbacks.

When you successfully grapple a creature, it takes 1d4 acid damage. As long as it remains grappled by you, the creature takes 1d4 acid damage at the start of it's turn. Additionally your movement speed is 0 until you release the grapple or until the creature frees itself. As an action you can eat through the non-magical armor or weapon of the creature you have grappled, and requires 2 rounds to complete (using your action to perform this task during both rounds). 

Your unarmed strikes deal 1d6 acid damage (this replaces your unarmed strike).

You can eat through 2-inch-thick, non-magical metal in 3 round.

You can eat through most materials with these exceptions: Gold, Glass, Plastic (where applicable), Platinum, Lead, and Mythril.

You cannot use any non-magical weapons or items unless they are made of a material that you cannot eat through, and regardless of magical or material you cannot use armor (you are a ball of fluid).

Coming into contact with any base liquid (e.g. baking soda, soap, bleach) removes all natural acid based damage you cause, prevents you from eating through any material, and reduces your walking movement speed to 5 and removes all other movement speeds until you have worked it out of your body. This can be done by an individual who aids you in removing it for 15 minutes or by yourself in 2 hours.

Gains resistance to piercing and acid damage from nonmagical attacks. Immune to being Blinded.

You don’t require sleep; however, you have to "rest" while being halve conscious. You must consume something every 24 hours or take a -1 to endurance per day you failed to consume anything (increasing your exhaustion by 1). You regain 1 endurance every day that you consume something (reducing your exhaustion by up to 1 every 24 hours).

You gain immunity to one status type on 5th, 9th, 11th, 13th, 15th and 17th level.

You gain immunity to Grappled, Deafened, Prone, Stunned, Restrained, Exhaustion.

In their true form Oozes have no eyes with which to see, however they can still perceive their environment out to a range of 60ft. through Blindsight, and a range of 120ft. through Tremorsense. Beyond that however they are blind.

When you aren't wearing armor, your AC is 11 + your Dexterity modifier. A shield's benefits apply as normal while you use your natural armor.

An Slime that takes cold damage has its speed halved, it cannot grapple (a grappled creature is immediately released), and looses Shapchanger until it has warmed back up (30 minutes without a heat source).

An Slime that takes heat damage cannot grapple (a grappled creature is immediately released) and looses Shapchanger until it has cooled down (10 minutes without a cooler).

You gain proficiency with two of the following skills of your choice: Deception, Insight, Perception, and Persuasion.

You gain proficiency with one tool of your choice.

You can enter an enemy's space and stop there. You can also move through a space as narrow as 1 inch wide without squeezing. Your movement speed is reduced by half rounded down in cold environments, and you have a -10 to your initiative. You can only equip magic items.

While grappling a creature, you take only half the damage dealt to you, and the creature you are grappling takes the other half. You can try to grapple any creature in your space and up to 5ft. away from you. You can grapple 1 + your proficency bonus targets.

You receive full damage if hit by attacks that deal fire or cold damage, additionally to the significant penalties you experience when exposed to fire or cold damage.

Your body effectively functions as a bag of holding that only you can access, only magic items can be stored amd equipped. However, if your body is placed into an extradimensional space, neither your body nor the extradimensional space is destroyed, and no gate to the Astral Plane is opened. An object can be stored in your body even if it is larger than your body, you can carry objackts up to your encumbrance limit. If your body is destroyed, any objects inside are destroyed without a trace.

You can grapple an opponent contesting with your Dexterity check contested by the target's Dexterity or Strength check. If you have a creature grappled, you can take an action in its turn and it can try to regain control at the start of his turn, by making a grapple contest again. While grappled the target takes 1d6 acid damage.

While grappling a creature, you take only half the damage dealt to you, and the creature you are grappling takes the other half. You can try to grapple any creature in your space and up to 5ft. away from you. You can grapple 1 + your proficency bonus targets.

You receive full damage if hit by attacks that deal fire or cold damage, additionally to the significant penalties you experience when exposed to fire or cold damage.

Depending on your progenitor ooze, you you gain additional traits and abilitys at the 11th level.

Black puddin: A black pudding is an ooze resembling a bubbling, heaping pile of thick black goo. Black pudding attack by grabbing, grappling, and constricting prey directly into their liquid-esque mass.

Juiblex: Juiblex was a demon lord of oozes and shapeless things, a being that exemplified the corruptive nature of the Abyss and that was almost glorious in its unrivaled obscenity. Ridiculed by its peers as "Lord of Nothing", the Faceless Lord was, even to them, a demon as revoltingly vile in body as it was inscrutably aberrant in mind. Juiblex is the sovereign of foulness and hunger, polluting and consuming everything in his wake.

Bukubukuchagama: Known as the Unsinkable and the embodiment of defensive abilities. Bukubukuchagama specializes in abilities for command and damage reduction.