Black Creeper

Amorphous. The black creeper can move itself through any opening large enough to fit the largest bones it contains without squeezing.

Foul. A creature that touches the black creeper or hits it with a melee attack while within 5 feet of it takes 4 (1d8) necrotic damage.

Spider Climb. The black creeper can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

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

Creatures inside the black creeper can not be seen and have total cover.

A creature within 5 feet of the black creeper can take an action to pull a creature or object out of the it. Doing so requires a successful DC 15 Strength check, and the creature making the attempt takes 10 (3d6) necrotic damage.

Multiattack. The black creeper makes one bite, squirt, or engulf attack and up to two claw attacks, or it makes up to four claw attacks.

Piercing Claw. Melee Weapon Attack: +8 to hit, reach 15 ft., one target. Hit: 15 (2d10+4) piercing damage plus 7 (2d6) necrotic damage. If the target is a creature the black creeper can pull the target up to 10 feet towards itself and the target is grappled (escape DC 15).

Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 20 (3d10+4) piercing damage plus 10 (3d6) necrotic damage. 

Squirt. The black creeper squirts its foul black slime on one creature it can see within 30 feet. The target must succeed on a DC 15 saving throw or take 10 (3d6) necrotic damage.

Engulf. The black creeper moves up to its speed. While doing so, it can enter Large or smaller creatures' spaces. Whenever the black creeper 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 5 feet back or to the side of the black creeper. A creature that chooses not to be pushed suffers the consequences of a failed saving throw.

On a failed save, the black creeper enters the creature's space, forms a tooth-lined maw and bites it, and the creature takes 20 (3d10+4) piercing damage plus 10 (3d6) necrotic damage and is engulfed. The engulfed creature can't breathe, is restrained, and takes 21 (6d6) necrotic damage at the start of each of the black creeper's turns. When the black creeper 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 black creeper.

The black creeper can only engulf up to two medium or four small creatures at a time.

Split. When a black creeper that is Medium or larger is subjected to lightning or slashing damage, it splits into two new black creepers if it has at least 10 hit points. Each new black creeper has hit points equal to half the original's, rounded down. New black creepers are one size smaller than the original.

Deadly Reach. In response to an enemy moving into its reach, the black creeper makes one claw attack against that enemy. If the attack hits, the black creeper can make a second claw attack against that target.

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

Bite Attack. The black creeper makes one bite attack against one creature it has grappled.

Squirt. The black creeper makes one squirt attack on one creature it can see within 30 feet.