Ambusher In the first round of a combat, the Acidic Blob has advantage on attack rolls against any creature it surprised.

Amorphous. The Acidic Blob can move through a space as narrow as 1 inch wide without squeezing.

Corrode Metal. Any nonmagical weapon made of metal that hits the Acidic Blob corrodes. After dealing damage, the weapon takes a permanent and cumulative -1 penalty to damage rolls. If its penalty drops to -5, the weapon is destroyed. Nonmagical ammunition made of metal that hits the Acidic Blob is destroyed after dealing damage. The Acidic Blob can eat through 2-inch-thick, nonmagical metal in 1 round.

Continual Growth. If a target is killed inside the Acidic Blob then it becomes larger by 5 feet by 5 feet.

Lunge Step. The Acidic Blob moves by using a lunge movement of shooting out a thin line of itself, up to 30 feet, and over the course of the other players turns it moves its whole body to that location. When this action is first made, all target at the targeted area must make a dexterity saving throw or fall prone and by grappled by the Acidic Blob.

Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.

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

Creatures inside the Acidic Blob can be seen but have total cover.

A creature within 5 feet of the Acidic Blob can take an action to pull a creature or object out of itself. Doing so requires a successful DC 15 Strength check, and the creature making the attempt takes 13 (4d6) acid damage.

The Acidic Blob can hold only two Large creature or up to eight Medium or smaller creatures inside it at a time.

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

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

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

On a failed save, the Blob enters the creature's space, and the creature takes 13 (4d6) acid damage and is engulfed. The engulfed creature can't breathe, is restrained, and takes 27 (8d6) acid damage at the start of each of the Blob's turns. When the Blob 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 Blob.

Life Leech. One Large or smaller creature that the Blob can see within 5 feet of it must succeed on a DC 15 Dexterity saving throw or be grappled (escape DC 15 strength). Until this grapple ends, the target is restrained and unable to breathe unless it can breathe water. In addition, the grappled target takes 30 (5d10) necrotic damage at the start of each of its turns. The Blob can grapple only two target at a time. The Blob takes half of the necrotic damage as hit points.

Magical Pseudopod. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: (2d6 + 2) bludgeoning damage plus (3d6)acid damage. If the target is wearing armor, its armor is partly corroded and takes a permanent and cumulative -1 penalty to the ac it offers. The armor is destroyed if the penalty reduces its AC to 0.

Slam. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 8 (1d10+3) bludgeoning damage plus (2d6) acid damage.

The Acidic Blob 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 Acidic Blob regains spent legendary actions at the start of its turn.

Body Slam. (Cost 2 Actions) Melee Weapon Attack: +15 to hit, reach 15 ft.. Hit: 8 (3d10+3) bludgeoning damage plus (3d6) acid damage. The area of the slam is 20 feet by 20 feet circle. All target must pass a dexterity saving throw or be Engulfed DC 22.

Soul Leech. (Costs 2 Actions) One Large or smaller creature that the Acidic Blob has Engulfed must make a Wisdom saving throw DC 20 or take 20 necrotic damage. The Acidic Blob takes the necrotic damage as hit points.