Ooze Master

Huge undead, lawful evil

Armor Class 9 (natural armor)

Hit Points 138 (12d12+60)

Speed 30 ft., climb 30 ft.

Saving Throws Int +7, Wis +4

Skills Arcana +7, Insight +4

Damage Resistances lightning, necrotic; bludgeoning, piercing, and slashing from nonmagical attacks

Damage Immunities acid, cold, poison

Condition Immunities blinded, charmed, deafened, exhaustion, frightened, paralyzed, poisoned, prone

Senses blindsight 120 ft.

Languages Common, Primordial, Thayan

Challenge 10 (5,900 XP)

Source. tales from the yawning portal, page 241

Undead Nature. The ooze master doesn’t require air, food, drink, or sleep.

Corrosive Form. A creature that touches the Ooze Master or hits it with a melee attack while within 5 feet of it takes 9 (2d8) acid damage. Any nonmagical weapon that hits the Ooze Master 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 that hits the Ooze Master is destroyed after dealing damage.

The Ooze Master can eat through 2-inch-thick, nonmagical wood or metal in 1 round.

Instinctive Attack. When the Ooze Master casts a spell with a casting time of 1 action, it can make one pseudopod attack as a bonus action.

Spellcasting. The Ooze Master is a 9th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 15, +7 to hit with spell attacks). It has the following wizard spells prepared:

Cantrips (at will): acid splash, friends, mage hand, poison spray

1st level (4 slots): charm person, detect magic, magic missile, ray of sickness

2nd level (3 slots): detect thoughts, Melf’s acid arrow, suggestion

3rd level (3 slots):fear, slow, stinking cloud

4th level (3 slots): confusion, Evard’s evard’s black tentacles

5th level (1 slot): cloudkill.

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

Actions

Pseudopod. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 13 (3d6 + 3) bludgeoning damage plus 10 (3d6) acid damage.

Reactions

Instinctive Charm. If a creature the Ooze Master can see makes an attack roll against it while within 30 feet of it, the Ooze Master can use a reaction to divert the attack if another creature is within the attack’s range. The attacker must make a DC 15 Wisdom saving throw. On a failed save, the attacker targets the creature that is closest to it, not including itself or the Ooze Master. If multiple creatures are closest, the attacker chooses which one to target. On a successful save, the attacker is immune to this Instinctive Charm for 24 hours. Creatures that can’t be charmed are immune to this effect.