Ancient white dracari

Amphibious. The dracari can breathe air and water.

Ice Walk. The dracari 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.

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

Spellcasting. The [dracari] is a spellcaster. Its spellcasting ability is [Intelligence] (spell save DC 21, +11 to hit with spell attacks). The [dracari] has following spells prepared:

At will: detect magic, Alarm, Arcane Eye

2/day each: hold monster, wall of ice

Regeneration. The dracari regains 15 hit points at the start of its turn if it has at least 1 hit point.

Magic Weapons. The dracari weapon attacks are magical.

Multiattack. The dracari can use its Frightful Presence. It then makes 4 Duel blads Attacks ore 2 Giant Bow Attacks.

Duel blads. Melee Weapon Attack: +12 to hit, reach 10 ft., 1 target. Hit: (2d8 + 8) [slashing] damage. 

Giant Bow. RangedWeapon Attack: +12 to hit, range 30/1200 ft., 1 target. Hit: (6d6 + 8) [piercing] damage. 

Bite. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 19 (2d10 + 8) piercing damage plus 9 (2d8) cold damage. 

Tail. Melee Weapon Attack: +14 to hit, reach 15 ft., one target. Hit: 17 (2d8 + 8) bludgeoning damage.

Frightful Presence. Each creature of the dracari's choice that is within 120 feet of the dracari's and aware of it must succeed on a DC 16 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 dracari exhales an icy blast in a 90-foot cone. Each creature in that area must make a DC 22 Constitution saving throw, taking 72 (16d8) cold damage on a failed save, or half as much damage on a successful one.

Enter the description for how bonus actions work for your monster here.

The dracari 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 dracari makes a Wisdom (Perception) check.

Tail Attack. The dracari makes a tail attack.

Bite Attack. The dracari makes a Bite attack.