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Cerberus Guardian


AC 20 (natural armor)
HP 310 (20d12 + 180; bloodied 155)
Speed 60 ft.

Proficiency +7; Maneuver DC 23
Saving Throws Str +15, Con +16, Int +5, Wis +11, Cha +9
Skills Perception +11
Damage Immunities acid, fire, poison, psychic; damage from nonmagical, non-adamantine weapons
Condition Immunities charmed, fatigue, frightened, paralyzed, petrified, poisoned
Senses truesight 90 ft., passive Perception 21
Languages understands the languages of its creator but can’t speak

Immutable Form. The guardian is immune to any effect that would alter its form.

Legendary Resistance (3/Day). When the guardian fails a saving throw while it has at least two heads active, it can choose to succeed instead. When it does so, one of its heads becomes inactive until the end of its next turn.

Multiple Heads. While the guardian has more than one head active, it has advantage on Perception checks and on saving throws against being blinded, deafened, stunned, and knocked unconscious, and it can’t be flanked.


Multiattack. The guardian makes three bite attacks, minus one for each of its inactive heads. Each bite must be against a different target.

Bite. Melee Weapon Attack: +15 to hit, reach 10 ft., one target. Hit: 27 (3d12 + 8) piercing damage.

Poison Tail. Melee Weapon Attack: +15 to hit, reach 15 ft., one target. Hit: 18 (3d6 + 8) piercing damage plus 10 (3d6) poison damage.


The guardian can take 3 legendary actions, minus one for each inactive head, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature’s turn. It regains spent legendary actions at the start of its turn.

Bronze Clangor (1/Round). The guardian’s tongue tolls in its bronze mouth like a bell. Each creature within 60 feet that can hear the clangor makes a DC 24 Constitution saving throw . On a failed save, the target takes 21 (6d6) thunder damage and is deafened for 1 minute. On a success, the target takes half damage and isn’t deafened. The guardian can’t use this legendary action if its bronze head is disabled.

Iron Breath (1/Round). The guardian breathes poison gas in a 60-foot cone. Each creature in the area makes a DC 24 Constitution saving throw . On a failed save, the target takes 24 (7d6) poison damage and is poisoned for 1 minute. On a success, the target takes half damage and isn’t poisoned. The guardian can’t use this legendary action if its iron head is disabled.

Stone Howl (1/Round). The guardian lets loose a spine-chilling howl. Each creature within 60 feet that can hear the howl must succeed on a DC 21 Wisdom saving throw or be frightened for 1 minute. The target must repeat the saving throw at the end of each of its turns. On a successful save, the effect on itself ends. On a failure, the creature is petrified. The guardian can’t use this legendary action if its stone head is disabled.

Tail. The guardian attacks with its poison tail.

The guardian obeys its master’s instructions to the letter. In combat, it rushes into a group of enemies so that it can make as many bite attacks as possible. It can’t use the same head twice in the same round, so it usually starts with Stone Howl, then uses Iron Breath and finally Bronze Clangor. On later turns, it may attack with its tail instead of using Stone Howl if most of its opponents are deafened.

Legends and Lore

With an Arcana or History check, characters can learn the following:

DC 15 Cerberus guardians are mighty constructs created by powerful spellcasters to protect their sanctums.

DC 20 A cerberus’s three heads deafen, poison, and frighten its foes. A creature frightened by the cerberus guardian might turn to stone.


Agontes, Brieris, Mr. Huggins, Rex


Cerberus guardians are among the mightiest constructs mortals have ever built. Only the most powerful lich or archmage can summon the magics required to create such a terrifying guardian. Cerberus guardians are also employed by the lords of Hell and the Abyss to guard secret planar gates.

Mage’s Best Friend. Unthinking and obedient, a cerberus guardian almost never runs berserk when damaged, as lesser guardians tend to do. It can operate for thousands of years and often continues its duties long after its creator has died.


1–3 Guarding an entrance

4 Chained to the entrance it guards (the chain allows the guardian to move up to 200 feet from the entrance)

5 Patrolling

6 Damaged, with one head inactive (choose randomly); barks at nothing and doesn’t notice intruders


1 Distant clang, like a bell]

2 An echoing howl, like that of a dog or wolf

3 Enormous canine paw prints

4 Stone statue (one of the guardian’s petrified victims)


Cerberus guardians usually guard portals and occasionally protect gates to Hell and other planes.

CR 23–30 cerberus guardian ; cerberus guardian with 1d6 death dogs or hound guardians

Monster Type Description

Constructs are beings that were built or made. Some are mindless machines, while others have some form of intelligence. Guardians are constructs.