Adult White Dragon (Improved)

Draconic Frost. The dragon ignores resistance to cold damage, its attacks are considered magical and add a d8 additional cold damage to its bite and claw attacks (Already applied to the 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.

Icy Cloak. The dragon's body naturally has a slippery cloak of ice. The dragon has 25 temporary hit points, while it has these hit points it has resistance to bludgeoning and fire damage. Using Cold Breath causes the dragon to gain 10 temporary hit points if it has none.

Keen Senses. The dragon has advantage on Wisdom (Perception) checks it makes that rely on hearing or smell.

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

Perfect Memories. The dragon does not have to roll Intelligence checks to remember anything it has learned, attained, killed or met.

Snow Camouflage. The dragon has advantage on Dexterity (Stealth) checks it makes in any terrain with ample snow or ice.

 Frozen: A creature who is frozen is stuck and has a hard time moving. A creature affected by this condition has the restrained condition, has disadvantage on Dexterity saving throws and becomes petrified (except with a vulnerability to fire) if it lasts longer than 1 minute. A creature or its ally can use its action to get rid of this condition.

Hindered: Causes a creature to have a 5ft reduction of movement speed.

Multiattack. The dragon can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws, or one with its bite and two with its Icicle Spear Attack.

Bite. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 17 (2d10 + 6) piercing damage plus 9 (2d8) cold damage and forces a DC 19 Constitution saving throw or be frozen

Claw. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) slashing damage and 4 (1d8) cold damage.

Icicle Spear. Ranged Weapon Attack: +11 to hit, range 60/120 ft., one target . Hit: 24 (4d8 + 6) cold damage, and causes that creature to be hindered. 

Tail. Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit: 15 (2d8 + 6) bludgeoning and it forces a DC 19 Strength saving throw  which knocks prone.

Consume Icicle. The white dragon eats a creature at least one size smaller than it who has become petrified by the frozen condition. When the dragon consumes a frozen creature that creature dies healing the creature for a (1d12 + 6) if tiny, (2d12 + 6) if small or medium and (3d12 + 6) if large.

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 14 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.

Cold Breath (Recharge 5–6). The dragon exhales an icy blast in a 60-foot cone. Each creature in that area must make a DC 19 Constitution saving throw, taking 54 (12d8) cold damage and become frozen on a failed save. On a success, they take half as much damage and do not get frozen. 

Ice Storm (1/Day):  If the dragon still has its Icy Cloak Feature it may use its bonus action to get rid of the remaining temporary hit points and to cause an ice storm. The white dragon casts Ice Storm at 5th level centered on itself DC 19, the spell adds 1 point of cold damage for every temporary hit points expended to one damage roll of the spell. The dragon automatically succeeds this saving throw taking no damage. Any creature frozen makes the saving throw with disadvantage.

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 19 Dexterity saving throw or take 13 (2d6 + 6) bludgeoning damage and be knocked prone. If a frozen fails they take an 10 (3d6) bludgeoning damage. The dragon can then fly up to half its flying speed without proccing opportunity attacks