Vince blue bigger dragon

Chromatic Awakening (Recharges after a Short or Long Rest).
If the greatwyrm would be reduced to 425 hit points, it recharges its Breath Weapon, and it regains an expended uses of Legendary Resistance. Additionally, the greatwyrm can now use the options in the "Mythic Actions" section for 1 hour.

Legendary Resistance (4/Day).
If the greatwyrm fails a saving throw, it can choose to succeed instead.

Unusual Nature.
The greatwyrm doesn't require food or drink.

Bonus Proficiencies
1st-level Combat Companion feature
The companion gains proficiency in Strength saving throws
if it doesn’t already have it.
Additionally, the companion gains proficiency in Athletics
and Intimidation.

Creature of War
1st-level Combat Companion feature
The companion gains proficiency with simple and martial weapons provided it has the ability to wield them. A companion that does not have hands, for example, cannot
fire a crossbow but could potentially grasp a sword or dagger in their jaws to wield that. A companion cannot use a weapon attack as part of its multiattack, unless such a use is part of its multiattack feature. The companion also selects one fighting style from the options available to the fighter class. It cannot select a fighting style that it is incapable of using. At 16th level, the companion selects one additional fighting
style from the options available to the fighter class. It cannot
choose a fighting style it is incapable of using.

Armored Ally
3rd-level Combat Companion feature
The companion gains proficiency with all armor and
shields. These typically need to be specially manufactured,
as few blacksmiths carry armors designed for non-humanoid creatures

Ability Score Improvement
4th-level Combat Companion feature
At 4th level and again at 8th, 11th, 14th, 17th, and 19th level,
the companion increases one ability score of your choice
by 2, or the companion increases two ability scores of your
choice by 1. The companion can’t increase an ability score
above 20 using this feature, nor is it able to select a feat in
place of improving its ability scores

Mariner (UA)
As long as you are not wearing heavy armor or using a shield, you have a swimming speed and a climbing speed equal to your normal speed, and you gain a +1 bonus to armor class.

Dueling (PHB).
When you are wielding a melee weapon in one hand and no other weapons, you gain a +2 bonus to damage rolls with that weapon.

Extra Attack
6th-level Combat Companion feature
The companion can attack twice, instead of once, whenever
it takes the attack action on its turn. The number of attacks increases to three when the
companion reaches 15th level. If the companion has the multi-attack action, it must choose whether it replaces the multi-attack or forgoes this feature

Keen Awareness
7th-level Combat Companion feature
The companion gains proficiency with Perception if it does not already have it and has advantage on Wisdom (Perception) checks used to locate a hostile creature. Additionally, the companion cannot be surprised while it is conscious.

Action Surge
10th-level Combat Companion feature
Starting at 10th level, the companion can push itself beyond
normal limits for a moment. On its turn, it can take one
additional action on top of its regular action and a possible
bonus action.
Once it uses this feature, it must finish a long rest before it
can use it again. Starting at 20th level, it can use this feature
twice before a rest, but only once on the same turn.

Extra Attack
6th-level Combat Companion feature
The companion can attack three times instead of once, whenever
it takes the attack action on its turn. If the companion has the multi-attack action, it must choose whether it replaces the multi-attack or forgoes this feature.(side note cannot uses the bite attack more than once)

Multiattack. The dragon makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +19 to hit, reach 15 ft., one target. Hit: 16 (2d10 + 11) piercing damage plus 11 (2d10) lightning damage.

Claw. Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit: 12 (2d8 + 11) slashing damage. If the target is a Huge or smaller creature, it is grappled (escape DC 21) and is restrained until this grapple ends. The greatwyrm can have only one creature grappled this way at a time.

Tail. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 12 (2d8 + 11) bludgeoning damage. If the target is a creature, it must succeed on a DC 27 Strength saving throw or be knocked prone.

Lightning Breath (Recharge 5–6). The dragon exhales lightning in an 500-foot line that is 15 feet wide. Each creature in that line must make a DC 27 Dexterity saving throw, taking 104 (16d12) lightning damage on a failed save, or half as much damage on a successful one.

Second Wind (uses 2)
2nd-level Combat Companion feature
The companion has stamina that goes beyond its untrained
counterparts. On its turn, it can use a bonus action to regain
hit points equal to 1d10 + its combat companion level. Once
it uses this feature, it must finish a short or long rest before it
can use it again.
The companion can use this feature twice between rests,
starting at 12th level

Legendary Action Uses: 3. Immediately after another creature's turn, The blue greatwyrm can expend a use to take one of the following actions. The blue greatwyrm regains all expended uses at the start of each of its turns.

Attack.
The greatwyrm makes one Claw or Tail attack.

Wing Attack (Costs 2 Actions).
The greatwyrm beats its wings. Each creature within 30 feet of it must succeed on a DC 27 Dexterity saving throw or take 17 (2d6 + 11) bludgeoning damage and be knocked prone. The greatwyrm can then fly up to half its flying speed.

Arcane Spear (Costs 3 Actions). The greatwyrm creates four spears of magical force. Each spear hits a creature of the greatwyrm's choice it can see within 120 feet of it, dealing 12 (1d8 + 9) force damage to its target, then disappears.

If the greatwyrm's Chromatic Awakening trait has activated in the last hour, it can use the options below as legendary actions.

Bite.
The greatwyrm makes one Bite attack.

Chromatic Flare (Costs 2 Actions).
The greatwyrm flares with elemental energy. Each creature in a 60-foot-radius sphere centered on the greatwyrm must succeed on a DC 26 Dexterity saving throw or take 22 (5d8) lightning damage.