Ancient Blue Dragon

Gargantuan dragon, lawful evil

Armor Class 22 (natural armor)

Hit Points 481 (26d20 + 208)

Speed 40 ft., fly 80 ft., swim 20 ft., climb 20 ft., burrow 40 ft.

str

29 (+9)

dex

10 (+0)

con

27 (+8)

int

18 (+4)

wis

17 (+3)

cha

25 (+7)

Saving Throws Dex +7, Wis +10

Skills Perception +17, Stealth +7

Damage Immunities lightning

Senses blindsight 60 ft., darkvision 120 ft., passive Perception 27

Languages Common, Draconic

Challenge 23 (50,000 XP)

Legendary Resistance (4/Day, or 5/Day in Lair). If the dragon fails a saving throw, it can choose to succeed instead.

Actions

Lightning Breath. Dexterity Saving Throw: DC 23, each creature in a 120-foot-long, 10-foot-wide Line. Failure: 88 (16d10) Lightning damage. Success: Half damage.

Multiattack. The dragon makes three Rend attacks. It can replace one attack with a use of Spellcasting to cast Shatter (level 3 version).

Rend. Melee Attack Roll: +16, reach 15 ft. 18 (2d8 + 9) Slashing damage plus 11 (2d10) Lightning damage.

Spellcasting. The dragon casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 22): - **At Will:** Detect Magic, Invisibility, Mage Hand, Shatter - **1/Day Each:** Scrying, Sending

Spellcasting (CHA, DC 22, +14 to hit)

At Will: Detect Magic, Invisibility, Mage Hand, Shatter

1/Day Each: Scrying, Sending

Attack Summary

Rend attackmelee

+16 to hit|2d8+9 slashing+2d10 lightning

Range: 15 ft.

Legendary Actions

The ancient blue dragon can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The ancient blue dragon regains spent legendary actions at the start of its turn.

Cloaked Flight. The dragon uses Spellcasting to cast Invisibility on itself, and it can fly up to half its Fly Speed. The dragon can't take this action again until the start of its next turn.

Sonic Boom. The dragon uses Spellcasting to cast Shatter (level 3 version). The dragon can't take this action again until the start of its next turn.

Tail Swipe. The dragon makes one Rend attack.