Gelatinous Cube

Large Ooze

STR	DEX	CON	INT	WIS	CHA
16 (+3)	2 (-4)	18 (+4)	1 (-5)	6 (-2)	1 (-5)

Skills:
Condition Immunities: blinded, charmed, deafened, fatigue, frightened, prone
Senses: blindsight 60 ft. (blind beyond this radius), passive Perception 8
Languages:

Engulfing Body: A creature that enters the cubes space is subjected to the saving throw and consequences of its Engulf attack.
Sunlight Sensitivity: While in sunlight, the cube has disadvantage on attack rolls.
Transparent: While the cube is motionless, creatures unaware of its presence must succeed on a DC 15 Perception check to spot it.
Ooze Nature: An ooze doesnt require air or sleep.

Pseudopod: Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (3d6) acid damage.
Engulf: The cube moves up to its Speed. While doing so it can enter Large or smaller creatures spaces. Whenever the cube enters a creatures space the creature makes a DC 13 Dexterity saving throw. If the creature is unaware of the cubes presence it makes its saving throw against Engulf with disadvantage. On a success the creature may use its reaction if available to move up to half its Speed without provoking opportunity attacks. If the creature doesnt move it is engulfed by the cube.
A creature engulfed by the cube takes 10 (3d6) acid damage, can't breathe, is restrained, and takes 10 (3d6) acid damage at the start of each of the cubes turns: It can be seen but has total cover. It moves with the cube. The cube can hold as many creatures as fit in its space without squeezing.
An engulfed creature can escape by using an action to make a DC 13 Strength check: On a success the creature moves to a space within 5 feet of the cube. A creature within 5 feet can take the same action to free an engulfed creature but takes 10 (3d6) acid damage in the process.