Ancient Dragonblood Ooze

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

Unyielding Movement - The ooze is unaffected by difficult terrain and can move through large structures without issue as its body simply slips by and around them. 

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

Multiattack. The ooze makes three Pseudopod attacks. The ooze can replace one Pseudopod attack with its Slime Breath, if available.

Pseudopod. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 25 (3d10 + 8) bludgeoning damage plus 14 (4d6) acid damage. If the target is a Large or smaller creature, it is grappled (escape DC 19). Until this grapple ends, the target takes 7 (2d6) acid damage at the start of each creatures turns.

Slime Breath (Recharge 6). The ooze expels a blob of its gelatinous mass, Range = 60ft, Radius = 30ft. Each creature in that area must make a DC 19 Dexterity saving throw. On a failed save, the creature takes 32 (6d10) acid damage and is pulled up to 30 feet straight toward the ooze. On a successful save, the creature takes half as much damage and isn’t pulled. The effected area is considered Difficult Terrain until the start of the ooze's next turn. 

Responsive Mitosis. As a Free Reaction to taking Damage, the ooze can divide its body in half and then each piece can move up to half of its speed without provoking Opportunity Attacks. Each piece of the ooze retains the same game statistics as the original creature, except they have half of its current HP when the split occurred.