Ancient Black Dragon

Size: Gargantuan Type: Dragon Alignment: chaotic evil Armor Class: 22 Hit Points: 367 Hit Dice: 21d20+147 Speed: "fly": 80, "swim": 40, "walk": 40 Challenge Rating: 21 Actions: ["desc": "The dragon can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.", "name": "Multiattack", "attack_bonus": 15, "damage_bonus": 8, "damage_dice": "2d10+2d8", "desc": "Melee Weapon Attack: +15 to hit, reach 15 ft., one target. Hit: 19 (2d10 + 8) piercing damage plus 9 (2d8) acid damage.", "name": "Bite", "attack_bonus": 15, "damage_bonus": 8, "damage_dice": "2d6", "desc": "Melee Weapon Attack: +15 to hit, reach 10 ft., one target. Hit: 15 (2d6 + 8) slashing damage.", "name": "Claw", "attack_bonus": 15, "damage_bonus": 8, "damage_dice": "2d8", "desc": "Melee Weapon Attack: +15 to hit, reach 20 ft., one target. Hit: 17 (2d8 + 8) bludgeoning damage.", "name": "Tail", "desc": "Each creature of the dragon's choice that is within 120 feet of the dragon and aware of it must succeed on a DC 19 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the dragon's Frightful Presence for the next 24 hours.", "name": "Frightful Presence", "desc": "The dragon exhales acid in a 90-foot line that is 10 feet wide. Each creature in that line must make a DC 22 Dexterity saving throw, taking 67 (15d8) acid damage on a failed save, or half as much damage on a successful one.", "name": "Acid Breath (Recharge 5-6)"] Special Abilities: ["desc": "The dragon can breathe air and water.", "name": "Amphibious", "desc": "If the dragon fails a saving throw, it can choose to succeed instead.", "name": "Legendary Resistance (3/Day)"]