This opalescent, symbiotic goo comes sealed in a jar and slowly shifts and moves, as if endlessly exploring the jar’s interior. To attune to this item, you must first drink the contents of the jar, unlocking the following properties:

Resistant. While attuned to Yensid's Sinister Ooze, you have resistance to poison, acid, and falling damage, and you are immune to the poisoned condition. If you arent wearing armor, The Ooze gives you an armor class of 13 plus dexterity.

Squishy. You have advantage on any Strength (Athletics) or Dexterity (Acrobatics) check you make to escape from being grappled.

Sticky. You can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Amorphous. As an action, you can cause your body to assume the amorphous qualities of the ooze. For the next minute, you (along with any equipment you are wearing or carrying) can move through a space as narrow as 1 inch wide without squeezing.

Pseudopod Attack. The ooze's feeding apendage provides a natural melee weapon attack that deals 1d6 bludgeoning plus 2d4 acid damage and counts as a natural weapon. The attack uses your Wisdom modifier for the attack and damage rolls, as the symbiote can be difficult to control.

Ooze Fall. A fall triggers a minute-long, complete merger between you and the symbiote. Should you hit the ground within that minute, the symbiotic bond allows you to splat relatively safely, reducing all impact damage by half.

Dual Nature. Any items or spells that affect oozes also affect you. Animals can detect the symbiote's unnatural nature and always start off as aggressive. All Wisdom (Animal Handling) checks are at disadvantage. The Ooze has blindsight out to 60 ft. and is always watching. This gives you proficiency in the Perception skill.

Hunger. You must eat double rations per day or the symbiote will feed off you. This parasitic nature prevents you from getting a full night's rest and you will suffer one level of exhaustion per day until properly fed. The ooze will digest anything organic that is consumed, leaving you unable to perform many bodily functions.

The Secret of the Ooze. The ooze can’t be removed from you while you are attuned to it, and you can’t voluntarily end your attunement to it. If you die while the ooze is inside you, it bursts out and engulfs your corpse, turning it into an intelligent Black Pudding allied with the Lich Yensid.

Notes: Bonus: Armor Class, Proficiency: Perception, Natural Weapon: Bludgeoning, Damage: Acid, Resistance: Poison, Resistance: Acid, Immunity: Poisoned, Disadvantage: Animal Handling, Symbiote