Gelatinous Wall A5E
CR 7 ooze
Huge ooze, chaotic evil
A creature that enters the cubes space is subjected to the saving throw and consequences of its Engulf attack.
An ooze doesnt require air or sleep.
While in sunlight, the cube has disadvantage on attack rolls.
While the cube is motionless, creatures unaware of its presence must succeed on a DC 15 Perception check to spot it.
Actions
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.
Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (3d6) acid damage plus 9 (2d6 + 2) bludgeoning damage.
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.
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 plus 9 (2d6 + 2) bludgeoning damage in the process.
Source: Monstrous Menagerie (EN Publishing) · License: OPEN GAME LICENSE Version 1.0a details