Chrono Slime

 Amorphous: The chrono slime can move through a space as narrow as 1 inch wide without squeezing.

Corrode Metal: The chrono slime can eat through 2-inch-thick, nonmagical metal in 1 round.

Chrono Bash: Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 11(3d6+2) bludgeoning damage. The target must make a DC 14 Con save. On failure, the target's mind becomes absorbed into a random time strand, and they become charmed. The target can choose to roll this save again for free every turn until they are freed.

Pseudopod: Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 13 (3d4 + 2) bludgeoning damage plus 9 (2d6) necrotic damage, and if the target is wearing nonmagical metal armour, its armour is partly corroded and takes a permanent and cumulative −1 penalty to the AC it offers. The armour is destroyed if the penalty reduces its AC to 10.

Reverse Splitting: Once the chrono slime has been split, if both of the halves have not been destroyed or broken down further by the end of its next turn, the two pieces merge back together to form the previous state, and the health is rerolled for that state, minus one die. This effect stacks for each time the chrono slime merges, and is reset after 8 hours.

Corrode Metal: Any nonmagical weapon made of metal that hits the chrono slime corrodes. After dealing damage, the weapon takes a permanent and cumulative −1 penalty to damage rolls. If its penalty drops to −6, the weapon is destroyed. Nonmagical ammunition made of metal that hits the ooze is destroyed after dealing damage.