Ancient Black Dragon

Gargantuan dragon, chaotic evil

Armor Class 22 (natural armor)

Hit Points 367 (21d20 + 147)

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

str

27 (+8)

dex

14 (+2)

con

25 (+7)

int

16 (+3)

wis

15 (+2)

cha

22 (+6)

Saving Throws Dex +9, Wis +9

Skills Perception +16, Stealth +9

Damage Immunities acid

Senses blindsight 60 ft., darkvision 120 ft., passive Perception 26

Languages Common, Draconic

Challenge 21 (33,000 XP)

Amphibious. The dragon can breathe air and water.

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

Actions

Acid Breath. Dexterity Saving Throw: DC 22, each creature in a 90-foot-long, 10-foot-wide Line. Failure: 67 (15d8) Acid damage. Success: Half damage.

Multiattack. The dragon makes three Rend attacks. It can replace one attack with a use of Spellcasting to cast Acid Arrow (level 4 version).

Rend. Melee Attack Roll: +15, reach 15 ft. 17 (2d8 + 8) Slashing damage plus 9 (2d8) Acid damage.

Spellcasting. The dragon casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 21, +13 to hit with spell attacks): - **At Will:** Detect Magic, Fear, Acid Arrow - **1/Day Each:** Create Undead, Speak with Dead, Vitriolic Sphere

Spellcasting (CHA, DC 21, +13 to hit)

At Will: Detect Magic, Fear, Acid Arrow

1/Day Each: Create Undead, Speak with Dead, Vitriolic Sphere

Attack Summary

Rend attackmelee

+15 to hit|2d8+8 slashing+2d8 acid

Range: 15 ft.

Legendary Actions

The ancient black 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 black dragon regains spent legendary actions at the start of its turn.

Cloud of Insects. Dexterity Saving Throw: DC 21, one creature the dragon can see within 120 feet. Failure: 33 (6d10) Poison damage, and the target has Disadvantage on saving throws to maintain Concentration until the end of its next turn. Failure or Success: The dragon can't take this action again until the start of its next turn.

Frightful Presence. The dragon uses Spellcasting to cast Fear. The dragon can't take this action again until the start of its next turn.

Pounce. The dragon moves up to half its Speed, and it makes one Rend attack.