The whole adventure path had a disturbingly large number of oozes in the game and Divinity Drive was no exception. Straight up conversion, nothing fancy.
Large ooze, unaligned
Armour Class 17 (prescience)
Hit Points 220 (16d12 + 32)
Speed 20ft., climb 20ft.
STR 17 (+3) DEX 18 (+4) CON 14 (+2)
INT 21 (+5) WIS 21 (+5) CHA 21 (+5)
Saving Throws Dex +7, lnt +9, Wis +9, Cha +9
Skills Deception +9, Insight +9, Perception +9
Damage Immunities acid, cold, lighting, psychic
Condition Immunities blinded, charmed, deafened, exhaustion, frightened, prone
Senses blindsight 120 ft. (blind beyond this radius), passive Perception 19
Languages Abyssal, Aklo, Common, Draconic, Infernal, Undercommon, Protean; telepathy 120ft.
Challenge 10 (5,900 XP)
Amorphous. The crèche guardian can move through a space as narrow as 1 inch wide without squeezing.
Neural Pulse. Creatures hit by a brain ooze’s tentacle must succeed at a DC 17 Constitution save or take 1d6 points of Intelligence damage and be staggered (1/2 move, -2 AC/DEX, no reactions, either 1 action or 1 bonus action, 1 melee/ranged only spells take two actions on a roll of 11+) for 1 minute. Each time a brain ooze causes Intelligence damage, it gains 5 temporary hit points.
Prescience. Limited precognitive abilities grant a brain ooze advantage on initiative checks, on Dexterity saves, and a bonus to its Armor Class (included). Brain oozes are never surprised or flat-footed.
Psychic Noise. The discordant psychic noise emitted by a brain ooze dazes nearby creatures. Each creature that starts its turn within 20 feet of the brain ooze and isn’t immune to psychic must succeed on a DC 17 Wisdom saving throw. On a failure, the creature can’t take reactions until the start of its next turn and rolls a d8 to determine what it does during its turn. On a 1 to 4, the creature does nothing. On a 5 or 6, the creature takes no action or bonus action and uses all its movement to move in a randomly determined direction. On a 7 or 8, the creature makes a melee attack against a randomly determined creature within its reach or does nothing if it can’t make such an attack. Whether or not the save is successful, that creature cannot be affected again by the same brain ooze’s psychic noise for 24 hours. An affected creature may attempt a new save to shake off the effect at the end of each of its turns.
Sneak Attack (1/Turn). The crèche guardian deals an extra 13 (4d6) damage when it hits a target with a tentacle attack and has advantage on the attack roll, or when the target is within 5 feet of an ally of the crèche guardian that isn’t incapacitated and the crèche guardian doesn’t have disadvantage on the attack roll.
Spider Climb. The crèche guardian can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.
Multiattack. The crèche guardian can make two tentacle attacks. In addition it may always make a psychic crush attack if available.
Tentacle. Melee Weapon Attack: +8 to hit, reach 10 ft., one target.
Hit: 21 (5d6 + 3) lightning damage plus neural pulse.
Psychic Crush (Recharge 5-6). The crèche guardian targets one creature that it can sense within 120 feet of it. The target must make a DC 17 Intelligence saving throw, taking 21 (6d6) psychic damage on a failed save, or half as much damage on a successful one.
Two slimy tentacles protrude from the sides of this brain-shaped mass of quivering ooze. The creature is unlikely to be a native of Pangaea and some wizards and other scholarly types believe they are the creation of the mind flayers or other Far Realm infused lunatics.