Ancient Bronze Dragon

Amphibious. The dragon can breathe air and water.

Legendary Resistance (3/Day). When the dragon fails a saving throw, it can choose to succeed instead. When it does, some of its scales fall away and dissolve into sea foam. If it has no more uses of this ability, its Armor Class is reduced to 19 until it finishes a long rest.

Oracle of the Coast. The dragon can accurately predict the weather up to 7 days in advance and is never considered surprised while conscious. Additionally, by submerging itself in a body of water and spending 1 minute in concentration, it can cast scrying, requiring no components. The scrying orb appears in a space in the same body of water.

Innate Spellcasting. The dragons spellcasting ability is Charisma (save DC 20). It can innately cast the following spells, requiring no material components. 3/day each:fog cloud, speak with animals,commune with nature, speak with plants, 1/day:control weather, etherealness

Multiattack. The dragon attacks with its bite and twice with its claws. In place of its bite it can use Lightning Pulse.

Bite. Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 31 (4d10 + 9) piercing damage plus 9 (2d8) lightning damage.

Claws. Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit: 22 (3d8 + 9) slashing damage.

Tail. Melee Weapon Attack: +16 to hit, reach 20 ft., one target. Hit: 22 (3d8 + 9) bludgeoning damage and the dragon pushes the target 10 feet away.

Trident (Humanoid Form Only). Melee or Ranged Weapon Attack: +16 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 12 (1d6 + 9) piercing damage.

Lightning Pulse. The dragon targets one creature within 60 feet forcing it to make a DC 23 Dexterity saving throw. The creature takes 22 (4d10) lightning damage on a failure or half damage on a success. If the initial target is touching a body of water all other creatures within 20 feet of it and touching the same body of water must also make the saving throw against this damage.

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

Lightning Breath. The dragon exhales lightning in a 120-foot-long 10-foot-wide line. Each creature in the area makes a DC 23 Dexterity saving throw taking 93 (16d10) lightning damage on a failed save or half damage on a success. A creature that fails the saving throw can't take reactions until the end of its next turn.

Ocean Surge. The dragon exhales a torrent of seawater in a 30-foot cone. Each creature in the area makes a DC 23 Strength saving throw. A creature that fails is pushed 40 feet away from the dragon and knocked prone while one that succeeds is pushed only 20 feet away and isnt knocked prone.

Change Shape. The dragon magically takes the shape of a humanoid or beast, or changes back into its true form. It reverts to its true form if it dies. Any equipment it is wearing or carrying is absorbed or borne by the new form (dragons choice). In the new form, the dragons stats are unchanged except for its size. It can't use Lightning Pulse, Breath Weapons, Tail Attack, or Wing Attack except in dragon form. In beast form, it can attack only with its bite and claws, if appropriate to its form. If the beast form is Large or smaller, the reach of these attacks is reduced to 5 feet. In humanoid form, it can attack only with its trident.

Tail Attack. When a creature the dragon can see within 10 feet hits the dragon with a melee attack, the dragon makes a tail attack against it.

The dragon can take 3 legendary actions. Only one legendary action can be used at a time and only at the end of another creatures turn. It regains spent legendary actions at the start of its turn.

Roar. Each creature of the dragons choice within 120 feet that can hear it makes a DC 20 Charisma saving throw. On a failure, it is frightened for 1 minute. A creature repeats the saving throw at the end of its turns, ending the effect on itself on a success. When it succeeds on a saving throw or the effect ends for it, it is immune to Roar for 24 hours.

Wing Attack. The dragon beats its wings. Each creature within 15 feet makes a DC 24 Dexterity saving throw. On a failure, it is pushed 10 feet away and knocked prone. The dragon can then fly up to half its fly speed.

Foresight (Costs 2 Actions). The dragon focuses on the many sprawling futures before it and predicts what will come next. Until the start of its next turn, it gains advantage on saving throws, and attacks against it are made with disadvantage.