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Ancient Blue Dragon

Gargantuan · Dragon · CR 25 · Chaotic Evil

Source. Monstrous Menagerie

407 (22d20+176)

Ability Scores

Core attributes and their modifiers.

STR

DEX

CON

INT

WIS

CHA

Overview

Category Monsters

Size Gargantuan

Type Dragon

Alignment Chaotic Evil

XP 75000

Initiative Bonus +0

Movement

Walk 40 ft (12.2 m)

Fly 80 ft (24.4 m)

Swim 40 ft (12.2 m)

Climb 20 ft (6.1 m)

Burrow 40 ft (12.2 m)

Crawl 20 ft (6.1 m)

Senses

Darkvision 120 ft (36.6 m)

Blindsight 60 ft (18.3 m)

Tremorsense 60 ft (18.3 m)

Passive Perception 24

Saving Throws

Dexterity +8 Constitution +16 Wisdom +11 Charisma +13

Skills

Perception +11 Stealth +8 Survival +11

Languages

Common, Draconic, two more

Resistances & Immunities

Damage Immunities

lightning

Traits

Desert Farer

The dragon ignores difficult terrain or obscurement caused by sand or gravel, even while flying. Additionally, it ignores the effects of extreme heat.

Dune Splitter

The dragon can remain submerged in sand and gravel for up to 4 hours. It has advantage on Stealth checks made to hide in this way, and Large or smaller creatures within 20 feet of its hiding place when it emerges must succeed on a DC 24 Dexterity saving throw or be blinded until the end of its next turn.

Innate Spellcasting

The dragons spellcasting ability is Charisma (save DC 21). It can innately cast the following spells, requiring no material components.
- 3/Day Each: Blur, Silent Image, Blight, Hypnotic Pattern
- 1/Day Each: Control Water, mirage arcane

Legendary Resistance (3/Day)

When the dragon fails a saving throw, it can choose to succeed instead. When it does, it sheds some of its scales, which turn to sand. If it has no more uses of this ability, its Armor Class is reduced to 20 until it finishes a long rest.

Actions

Arc Lightning

The dragon targets a creature within 60 feet forcing it to make a DC 24 Dexterity saving throw. The creature takes 22 (4d10) lightning damage on a failure or half damage on a success. Also on a failure the lightning jumps. Choose a creature within 30 feet of the target that hasnt been hit by this ability on this turn and repeat the effect against it possibly causing the lightning to jump again.

Bite

+17 to hit, reach 15 ft (4.6 m). Hit: 4d10+9 plus 2d8 lightning damage.

Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 31 (4d10 + 9) piercing damage plus 9 (2d8) lightning damage.

Claw

+17 to hit, reach 10 ft (3 m). Hit: 3d8+9 slashing damage.

Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit: 22 (3d8 + 9) slashing damage.

Lightning Breath

Recharge 5–6

The dragon exhales a 120-foot-long 10-foot-wide line of lightning. Each creature in that area makes a DC 24 Dexterity saving throw taking 94 (17d10) lightning damage on a failed save or half damage on a success. A creature that fails the save can't take reactions until the end of its next turn.

Multiattack

The dragon attacks once with its bite and twice with its claws. In place of its bite attack it can use Arc Lightning.

Tail

+17 to hit, reach 20 ft (6.1 m). Hit: 3d8+9 bludgeoning damage.

Melee Weapon Attack: +17 to hit, reach 20 ft., one target. Hit: 22 (3d8 + 9) bludgeoning damage and the dragon pushes the target 10 feet away.

Reactions

Tail Attack

When a creature the dragon can see within 10 feet hits the dragon with a melee attack, the dragon makes a tail attack against it.

Legendary Actions

Quake

Cost 2

The dragon uses its Quake action.

Roar

Cost 1

Each creature of the dragons choice within 120 feet that can hear it makes a DC 21 Charisma saving throw. On a failure, it is frightened for 1 minute. A creature repeats the saving throw at the end of its turns, ending the effect on itself on a success. When it succeeds on a saving throw or the effect ends for it, it is immune to Roar for 24 hours.

The dragon can take 3 legendary actions

Cost 1

Only one legendary action can be used at a time and only at the end of another creatures turn. It regains spent legendary actions at the start of its turn.

Wing Attack

Cost 1

The dragon beats its wings. Each creature within 15 feet makes a DC 24 Dexterity saving throw. On a failure, it is pushed 10 feet away and knocked prone. The dragon can then fly up to half its fly speed.

About Ancient Blue Dragon

Ancient Blue Dragon is a gargantuan dragon with a Challenge Rating of 25. It has a chaotic evil alignment.

In combat, this creature maintains an Armor Class of 22 and possesses 407 hit points (derived from 22d20+176).

Ancient Blue Dragon has communication capabilities including Common, Draconic, two more. This allows it to interact verbally with various creatures and characters.

GM Tips: Using Ancient Blue Dragon

4 tips available

When using Ancient Blue Dragon in your D&D 5e campaign, consider these tactical approaches:

Flight Control Strategy: Target flying creatures with spells like 'Hold Person', 'Web', or 'Grease' to ground them. Without flight restriction, they can escape melee range easily. Consider area denial spells below their flight altitude to force them into disadvantageous positions.
Burrowing Tactics: This creature can burrow at 40 ft. It can ambush from underground or escape combat by digging. Use 'Earthbind' or create difficult terrain to limit burrowing. Consider fighting in areas without soft ground.
Aquatic Combat: This creature can swim at 40 ft. It has advantage in water environments. Consider fighting on land or using water-based spells against it.
Lightning Damage Awareness: Lightning attacks often have long range and high speed. Advise players to use cover and avoid metal armor/weapons. Water surfaces amplify lightning damage - avoid fighting near water.

Player Guide: Facing Ancient Blue Dragon

4 strategies available

When your party encounters this creature, keep these strategies in mind:

Counter Flight Advantage: This creature can fly! Use ranged attacks, reach weapons, or spells like 'Thunderwave' to push it away. Consider 'Gust of Wind' or 'Earthbind' to ground it. Melee characters need fly speed or flight magic to engage.
Burrowing Defense: This creature can burrow at 40 ft! It can ambush from underground. Use 'Earthbind', create difficult terrain, or fight on hard surfaces. 'Stone Shape' can seal burrows.
Aquatic Combat Defense: This creature can swim at 40 ft! It has advantage in water. Fight on land if possible. Use 'Control Water' or drain water sources to limit its mobility.
Lightning Damage Protection: This creature deals lightning damage! Avoid metal armor and weapons. Use cover and avoid water surfaces. 'Iron Skin' or 'Protection from Energy' can help.

Encounter Building Calculator

Standard Party Encounter (4-5 characters):

This creature is a medium encounter for a party of 4 characters of level 25.

High-Level Solo Encounter:

This creature is too powerful for a single level-20 character. You need 3.0 character(s) at maximum level (20) to face this creature.

Experience Point Thresholds:

Medium: 65,000 XP
Hard: 97,500 XP
Deadly: 130,000 XP

Based on D&D 5e Dungeon Master's Guide encounter building guidelines. CR roughly equals party level for medium encounters.

Frequently Asked Questions

What is the challenge rating of Ancient Blue Dragon?: Ancient Blue Dragon has a Challenge Rating of 25, making it appropriate for parties of level 25.0.
What type of creature is Ancient Blue Dragon?: Ancient Blue Dragon is a Gargantuan Dragon, which affects how certain spells and abilities interact with it.
What languages does Ancient Blue Dragon speak?: Ancient Blue Dragon can communicate in Common, Draconic, two more.