Ancient Boreal Dragon
Gargantuan Dragon, chaotic neutral
Armor Class 22 (natural armor)
Hit Points 407 (22d20+176)
Speed fly +80, swim +30, walk +40
Challenge 24
Saving Throws cha +11, con +15, dex +7, wis +11
Skills stealth +7, athletics +16, perception +18
Damage Resistances cold
Damage Immunities fire
Senses blindsight 60 ft., darkvision 120 ft., passive Perception 28
Languages Draconic, Giant
Special Abilities
Ember Wreath (1/Day). As a bonus action, the boreal dragon wreathes its body in searing blue and white embers. The embers last for 1 minute or until the dragon uses its breath weapon. A creature that enters or starts its turn in a space within 30 feet of the dragon must make a DC 23 Constitution saving throw, taking 10 (3d6) fire damage on a failed save, or half as much damage on a successful one. If a creature fails the saving throw by 5 or more, it suffers one level of exhaustion as the water is sapped from its body by the unrelenting heat.
Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.
Actions
Multiattack. The dragon can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.
Bite. Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 20 (2d10 + 9) piercing damage.
Claw. Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit: 16 (2d6 + 9) slashing damage.
Tail. Melee Weapon Attack: +16 to hit, reach 20 ft., one target. Hit: 18 (2d8 + 9) bludgeoning damage.
Frightful Presence. 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.
Cinder Breath (Recharge 5-6). The dragon exhales a 90-foot cone of superheated air filled with blue-white embers. Each creature in that area must make a DC 23 Dexterity saving throw, taking 88 (16d10) fire damage on a failed save, or half as much damage on a successful one.
Legendary Actions
The dragon can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature’s turn. The dragon regains spent legendary actions at the start of its turn.
Detect. The dragon makes a Wisdom (Perception) check.
Tail Attack. The dragon makes a tail attack.
Wing Attack (Costs 2 Actions). The dragon beats its wings. Each creature within 15 feet of the dragon must succeed on a DC 23 Dexterity saving throw or take 16 (2d6 + 9) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.
Source: Tome of Beasts 2 · OGL/Open