Ooze Cube. The cube takes up its entire space. Other creatures can enter the space, but a creature that does so is subjected to the cube's Engulf and has disadvantage on the saving throw.

Creatures inside the cube can be seen but have total cover.

A creature within 5 feet of the cube can take an action to pull a creature or object out of the cube. Doing so requires a successful DC 17 Strength check, and the creature making the attempt takes 18 (6d6) acid damage.

The cube can hold only one Large creature or up to four Medium or smaller creatures inside it at a time.

Transparent. Even when the cube is in plain sight, it takes a successful DC 17 Wisdom (Perception) check to spot a cube that has neither moved nor attacked. A creature that tries to enter the cube's space while unaware of the cube is surprised by the cube.

Pseudopod. Melee Weapon Attack: +9 to hit, reach 15 ft., one creature. Hit: 18 (6d6) acid damage.

Engulf. The cube moves up to its speed. While doing so, it can enter Huge or smaller creatures' spaces. Whenever the cube enters a creature's space, the creature must make a DC 15 Dexterity saving throw.

On a successful save, the creature can choose to be pushed 10 feet back or to the side of the cube. A creature that chooses not to be pushed suffers the consequences of a failed saving throw.

On a failed save, the cube enters the creature's space, and the creature takes 18 (6d6) acid damage and is engulfed. The engulfed creature can't breathe, is restrained, and takes 34 (10d6) acid damage at the start of each of the cube's turns. When the cube moves, the engulfed creature moves with it.

An engulfed creature can try to escape by taking an action to make a DC 15 Strength check. On a success, the creature escapes and enters a space of its choice within 10 feet of the cube.

The Acid Barge can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The Acid Barge regains spent legendary actions at the start of its turn.

Expel. The Acid Barge shoots a glob of acid to a space within 50ft of it, creating a 20ft space of rough terrain that also deals 2d8 acid damage to creatures that move over it for the first time in a round.

Pseudopod. The Acid Barge makes a pseudopod attack.

Corrode. The Acid Barge emanates gases that damage any metals within 30 ft of it. Any creature that hits the Acid Barge or is within it has all of their non-magic metals become -1 items. They can be reduced this way down to -4, and at -5, are destroyed. This lasts for 3 Turns (Not rounds).