ancient ooze

Amorphous. The pudding can move through a space as narrow as 1 inch without expending extra movement to do so.

Corrosive Form. A creature that hits the pudding with a melee attack roll takes 4 (1d8) Acid damage. Nonmagical ammunition is destroyed immediately after hitting the pudding and dealing any damage. Any nonmagical weapon takes a cumulative −1 penalty to attack rolls immediately after dealing damage to the pudding and coming into contact with it. The weapon is destroyed if the penalty reaches −5. The penalty can be removed by casting the Mending spell on the weapon.

In 1 minute, the pudding can eat through 2 feet of nonmagical wood or metal.

Spider Climb. The pudding can climb difficult surfaces, including along ceilings, without needing to make an ability check.

adaptability. when the black pudding takes damage from a damage type that isn't psychic, piercing, bludgeoning and slashing damage it gain a resistance to that damage until the start of its next turn. this can only happen once per turn and the other black puddings get resistance to the damage as well but ends when the original turn comes starts.

Dissolving Pseudopod. Melee Attack Roll: +5, reach 10 ft. Hit: 17 (2d8 + 3) Acid damage. Nonmagical armor worn by the target takes a −1 penalty to the AC it offers. The armor is destroyed if the penalty reduces its AC to 10. The penalty can be removed by casting the Mending spell on the armor.

slime throw.  the ooze does a ranged attack with a range of 120ft and it does 1d12 acid damage and it then the ooze makes a small ancient ooze with 5 hit points and the creature that made this attack takes 5 damage

Split. Trigger: While the pudding is Large or Medium and has 10+ Hit Points, it becomes Bloodied or is subjected to Lightning or Slashing damage. Response: The pudding splits into two new ancient ooze. Each new pudding is one size smaller than the original pudding and acts on its Initiative. The original pudding’s Hit Points are divided evenly between the new puddings (round down).