Ancient Black Dragon

Gargantuan dragon · CR 21 · 33,000 XP

22 AC · 367 HP

Roll the Ancient Black Dragon

Rend

Acid Breath DC 22 DEX

Press a roll button. The dice land here.

Stat block

Type: Gargantuan dragon, chaotic evil
Armor Class: 22
Hit Points: 367 (21d20 + 147)
Speed: 40 ft., fly 80 ft., swim 40 ft.
Challenge: 21 (33,000 XP), proficiency +7
Immunities: acid
Senses: darkvision 120 ft., blindsight 60 ft., passive perception 26
Languages: Common, Draconic

STR	DEX	CON	INT	WIS	CHA
27	14	25	16	15	22

Ancient Black Dragon odds against your Armor Class

Chance to hit, then average damage per attack once misses and critical hits are counted.

Attack	AC 12	AC 14	AC 15	AC 16	AC 18	AC 20
Rend (+15)	95% 25.6 dmg	95% 25.6 dmg	95% 25.6 dmg	95% 25.6 dmg	90% 24.3 dmg	80% 21.7 dmg
Full turn (3 attacks)	76.8 dmg	76.8 dmg	76.8 dmg	76.8 dmg	72.9 dmg	65.1 dmg

Ancient Black Dragon hit points

The stat block uses the average, 367. Rolled, 21d20 + 147 lands anywhere from 168 to 567.

168chance of each total for 21d20 + 147567

Hit points	Chance
268 or more	>99%
368 or more	50%
467 or more	<1%
527 or more	<1%

Roll 21d20 + 147 on its own with the d20 roller, or weigh it up on the dice calculator.

Traits

Amphibious. The dragon can breathe air and water.

Legendary Resistance. If the dragon fails a saving throw, it can choose to succeed instead.

Actions

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. Hit: 17 () Slashing damage plus 9 () Acid damage.

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

Legendary actions

Cloud of Insects. Dexterity Saving Throw: DC 21, one creature the dragon can see within 120 feet. Failure: 33 () 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.

Other CR 21 monsters

Ancient Copper Dragon Lich Solar

This page includes material from the System Reference Document 5.2.1 (“SRD 5.2.1”) by Wizards of the Coast LLC, available at dndbeyond.com/srd. The SRD 5.2.1 is licensed under the Creative Commons Attribution 4.0 International License. The averages, odds and tables are ours.