Colorless Greatwrym

Eternal Flare (Recharges after a Short or Long Rest). If the Greatwyrm would be reduced to 0 hit points, it uses its Breath Weapon. on hit the Greatwrym heals back double of all damage dealt. Award a party an additional 105,000 XP (210,000 XP total) for defeating the Greatwyrm after its Eternal Flare activates.

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

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

Bite. Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: 22 (3d10 + 8) piercing damage plus 5 (2d6) necrotic damage.

Claw. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 20 (3d6 + 8) slashing damage.

Tail. Melee Weapon Attack: +18 to hit, reach 20 ft., one target. Hit: 22 (3d8 + 8) slashing 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 20 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.

Black Flare Breath Weapon (Recharge 5–6). The dragon exhales Black and Purple Fire in a 90-foot line that is 10 feet wide. Each creature in that line must make a DC 24 Dexterity saving throw, taking 70 (10d12) Fire damage and 10 (2d8) Necrotic damage on a failed save, or half as much damage on a successful one.

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.

Attack. The Greatwyrm makes one claw or tail attack.

Wing Attack (Costs 2 Actions). The dragon beats its wings. Each creature within 15 feet of the dragon must succeed on a DC 24 Dexterity saving throw or take 15 (2d6 + 8) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.

Shed Flame (Costs 3 Actions): The dragon spews flame on the ground beneath itself. all terrain within 60ft of the dragon becomes covered in black and purple flame. Any creature on the ground within the flames must succeed on a DC 22 Dexterity saving throw of take 30  (10d6) Fire damage and be set on fire.

If the greatwyrm’s Eternal Flare trait has activated in the last hour, it can use the options below as legendary actions.

Bite. The greatwyrm makes one Bite attack.

Colorless Lance (Costs 3 Actions). The greatwyrm creates four arks of energy. Each ark hits a creature of the greatwyrm’s choice it can see within 120 feet of it, dealing 12 (1d8 + 8)damage of its choosing to its target, then disappears.