Celestial Cube

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 try to pull a creature or object out of the cube. Doing so requires a successful DC 15 Strength check, and the creature making the attempt takes 21 (6d6) radiant damage.

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

Touch. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 21 (6d6) radiant damage.

Engulf. The cube moves up to its speed. While doing so, it can enter Gargantuan or smaller creatures' spaces without counting them as difficult terrain. Whenever the cube enters a creature's space, the cube can force the creature to make a DC 15 Dexterity saving throw.

On a successful save, or if the cube doesn't force the creature to make the save, can choose to be pushed 5 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 if the cube forced the creature to make the save.

On a failed save, the cube enters the creature's space, and the creature takes 21 (6d6) radiant damage and is engulfed. The engulfed creature can't breathe, is restrained, and takes 42 (12d6) radiant 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 5 feet of the cube.