While there’s a huge variety of unique monsters in the official Dungeons and Dragons sourcebooks, you’ll find that there’s quite a bell curve when it comes to their Challenge Ratings. Most of the enemies fall somewhere in the middle, with few supernaturally strong options.  

So what are your options when running a high-level party? What creatures are left that can truly challenge your players? 

Here are some of the most difficult, dangerous enemies in D&D canon to use at your table. 

10. Zaratan, CR 22

Massive turtles made of earth and stone, Zaratans are capable of toppling cities and causing catastrophic earthquakes without even pausing to notice. Their attacks do pretty decent damage, and their ability to retract into their shell and regain hit points makes them even more difficult. 

These elder elementals pose a unique threat to settlements, cities, and villages. With Earth-Shaking Movement, they can use a bonus action to send a shock wave that creates Difficult Terrain and deals 100 thunder damage to all structures in range. Combine this with their Siege Monster trait, which gives them double damage against all objects and structures, and you have a hugely destructive force on your hands. 

This can add more compelling context to an encounter and increase the stakes, with players battling the Zaratan in an attempt to prevent the destruction of a nearby settlement

Zaratan Details:

https://5e.tools/bestiary/zaratan-mtf.html 

• Challenge Rating: 22
• Armor Class: 21
• Hit Points: 307 
• Damage Vulnerabilities: thunder
• Damage Resistances: cold, fire, lightning; bludgeoning, piercing, and slashing from nonmagical attacks
• Damage Immunities: poison
• Condition Immunities: exhaustion, paralyzed, petrified, poisoned, stunned

9. Elder Tempest, CR 23

A  storm serpent made from clouds, rain, wind, and lightning, the Elder Tempest causes a downpour of rain on the land beneath it and sends bolts of lightning to strike the earth  – certainly an atmospheric setting for an epic battle. 

The Elder Tempest’s various elemental attacks and effects can be devastating to its adversaries. It can control the lightning itself, inflicting 6d8 damage with Lightning Storm and 3d10 with Lightning Strike. 

It can also be an incredibly difficult monster to hit, as its ability to fly means it can constantly move out of range of the player's attacks. Its Screaming Gale Legendary Action also flings adversaries 60 feet away from it in addition to inflicting 4d10 damage.

Elder Tempest Details:

https://5e.tools/bestiary/elder-tempest-mtf.html 

• Challenge Rating: 23
• Armor Class: 19
• Hit Points: 264
• Damage Resistances: bludgeoning, piercing, and slashing from nonmagical attacks
• Damage Immunities: lightning, poison, thunder 
• Condition Immunities: exhaustion, grappled, paralyzed, petrified, poisoned, prone, restrained, stunned 

8. Kraken, CR 23 

The Kraken’s aquatic nature already makes it a difficult encounter, as players will probably have to fight the monster underwater. This gives the adventurers disadvantage on most attacks and reduced range on weapon attacks. 

Krakens can also conjure and control storms, creating difficult but atmospheric environments during encounters. Their lightning storm feature creates three bolts of lightning, each of which can strike a target within 120 feet of it. 

Kraken Details:

https://roll20.net/compendium/dnd5e/Kraken#content 

• Challenge Rating: 23
• Armor Class: 18
• Hit Points: 472
• Damage Immunities: lightning; bludgeoning, piercing, and slashing from nonmagical attacks
• Condition Immunities: frightened, paralyzed

7. Ancient Red Dragon, CR 24

Any of the ancient dragons would make for a challenging encounter, but the Ancient Red Dragon is one of the toughest with a Challenge Rating of 24 and 546 hit points 

They usually live in high mountains or rocky terrain and can use their different lair actions to create a magma geyser, release volcanic gas, or cause an earthquake. Their most powerful attack is their Fire Breath, which is a 90-foot cone of fire that inflicts 26d6 fire damage. 

Ancient Red Dragon Details:

https://roll20.net/compendium/dnd5e/Ancient%20Red%20Dragon#content 

• Challenge Rating: 24
• Armor Class: 22
• Hit Points: 546
• Damage Immunities: Fire 

6. Marut, CR 25

Marut were created to enforce agreements made in the Hall of Concordance. The golden discs in the center of their chests are the contracts they are bound to enforce, and they will seek to punish any party who has broken the terms of their agreement. 

Marut have 432 hit points, magic resistance, and immunity to any spell or effect that would alter their  form. Both of their attacks are either difficult or impossible to avoid. For example, their Unerring Slam attack automatically hits for 60 force damage and their other attack, Blazing Edict, automatically deals 45 radiant damage with no chance of a saving throw and forces each target to make a DC 20 wisdom saving throw or be stunned.

They have the benefit of flight, legendary resistance, and the ability to plane shift out of the battle if it seems like they are going to lose. 

Marut Details:

https://5e.tools/bestiary/marut-mtf.html

• Challenge Rating: 25
• Armor Class: 22 
• Hit Points: 432
• Damage Resistances: thunder; bludgeoning, piercing, and slashing from nonmagical attacks
• Damage Immunities: poison
• Condition Immunities: charmed, frightened, paralyzed, poisoned, unconscious

5. Demogorgon, CR 26

The Demogorgon is one of the formidable demon lords. This abomination has an ape-like torso, tentacled arms, and two ferocious heads – which gives the monster advantage on saving throws against being blinded, deafened, stunned, or knocked unconscious. 

The very gaze of the Demogorgon drives one mad, which means the players must fight the demon lord while being unable to look directly at it. If they do, they could become stunned, charmed, or confused. 

In addition to the Demogorgon’s innate spellcasting, legendary resistance, and magical resistance, it’s tentacle attack reduces the target's maximum hp. 

Demogorgon Details:

https://5e.tools/bestiary/demogorgon-mtf.html 

• Challenge Rating: 26
• Armor Class: 22
• Hit Points: 406
• Damage Resistances: cold, fire, lightning
• Damage Immunities: poison, and nonmagical bludgeoning, piercing and slashing 
• Condition Immunities: charmed, exhausted, frightened, poisoned 

4. Zariel, CR 26

A former angel who was corrupted by the influence of the Nine Hells, Zariel is an intimidating and intelligent adversary. 

She has natural regeneration abilities which means she can use her 150 fly speed to retreat from combat when she gets dangerously low on hit points, regenerate, and then re-engage. 

Any of her weapon attacks that hit do an extra 8d8 fire damage, her Horrid Touch inflicts 8d10 necrotic damage and makes the target poisoned, blinded, and deafened, and her Immolating Gaze legendary action inflicts 4d10 damage. 

Zariel Details:

https://5e.tools/bestiary/zariel-mtf.html 

• Challenge Rating: 26
• Armor Class: 21
• Hit Points: 580
• Damage Resistances: cold, fire, radiant; bludgeoning, piercing, and slashing from nonmagical attacks that aren't silvered
• Damage Immunities: necrotic, poisoned 
• Condition Immunities: charmed, exhaustion, frightened, poisoned 

3. Orcus, CR 26

Orcus is one of the most terrifying enemies you can encounter in Dungeons and Dragons. The Demon Prince is notoriously powerful, even without taking the army of undead he commands into consideration. 

His innate spellcasting gives him the ability to cast some absolutely brutal spells including Circle of Death, Finger of Death, Power Word Kill, and Time Stop, but his most powerful feature is without a doubt his wand.

The legendary Wand of Orcus lets him conjure up to 500 hit points of undead creatures to fight on his behalf. Imagine fighting not just Orcus, but the multiple liches he summoned to destroy his adversaries for him. 

Orcus Details:

https://5e.tools/bestiary/orcus-mtf.html 

• Challenge Rating: 26 
• Armor Class: 17, 20 with the Wand of Orcus
• Damage Resistances: cold, fire, lighting 
• Damage Immunities: necrotic, poison; bludgeoning, piercing and slashing damage that is nonmagical 

2. Tarrasque, CR 30 

The CR 30 Tarrasque is a legendarily difficult monster in D&D canon, though the 5th edition version is a little weaker than previous editions. Still, only the most experienced of adventurers can even have a chance against it. 

The Tarrasque has a sturdy 676 hit points and a litany of immunities and defensive abilities that make it difficult to take down. For example, its Reflective Carapace neutralizes and even potentially reflects back spells that require a ranged attack roll, line spells, and magic missile. In addition, they’re immune to fire, poison, bludgeoning, slashing, and piercing damage from any nonmagical item.

Tarrasque Details:

https://5e.tools/bestiary/tarrasque-mm.html 

• Challenge Rating: 30
• Armor Class: 25
• Hit Points: 676
• Damage Immunities: fire, poison; bludgeoning, piercing, and slashing from nonmagical attacks
• Condition Immunities: charmed, frightened, paralyzed, poisoned.

1. Tiamet, CR 30     

By the time players reach level 20, their power can rival that of the gods. So what’s left to challenge them beyond an actual deity? 

A draconic goddess and mother of all evil dragons, Tiamet is the most powerful adversary out there with an officially released stat block. While she shares her 30 CR with the Tarrasque, she really is on a whole different level of power. 

With a ton of immunities and defenses, she’s completely immune to any spells below 6th level and consistently regenerates 30 hit points a turn. She can cast Divine Word three times a day and because of her multiple heads, she can take one reaction per turn rather than only one per round. Combine this with her 120 feet breath weapons, and you have a monster that can challenge even the most optimized level 20 party. 

Tiamet Details:

https://5e.tools/bestiary/tiamat-rot.html 

• Challenge 30
• Armor Class 25
• Hit Points 615
• Speed 60 ft., fly 120 ft.
• Damage Immunities acid, cold, fire, lightning, poison; bludgeoning, piercing, and slashing from nonmagical attacks
• Condition Immunities blinded, charmed, deafened, frightened, poisoned, stunned

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