Adult Two-Headed Dragon

Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Multiple Heads. The dragon has two heads of white and silver dragons. While it has more than one head, the dragon has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious

Reactive Heads. For each head the dragon has beyond one, it gets an extra reaction that can be used only for opportunity attacks.

Ice Walk. The dragon can move across and climb icy surfaces without needing to make an ability check. Additionally, difficult terrain composed of ice or snow doesn't cost it extra movement.

Multiattack. The dragon can use its Frightful Presence. It then makes four attacks: two with its bite and two with its claws. It can instead use both of its breath weapons.

Bite. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 19 (2d10 + 7) piercing damage plus 4 (1d8) cold damage.

Claw. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 15 (2d6 + 7) slashing damage.

Tail. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 17 (2d8 + 7) 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.

Breath Weapons (Recharge 5–6). The dragon uses one of the following breath weapons.

Cold Breath. The dragon exhales an icy blast in a 60-foot cone. Each creature in that area must make a DC 20 Constitution saving throw, taking 63 (14d8) cold damage on a failed save, or half as much damage on a successful one.

Paralyzing Breath. The dragon exhales paralyzing gas in a 60-foot cone. Each creature in that area must succeed on a DC 20 Constitution saving throw or be paralyzed 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.

The 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 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 10 feet of the dragon must succeed on a DC 21 Dexterity saving throw or take 15 (2d6 + 7) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.

Breath Weapon (Costs 3 Actions). The dragon uses one of its breath weapons, but loses one of its reactions until the following turn.