You can get all the features below if you’re an ancient blue dragon 5e user, including the Traits, actions, legendary actions, and the attributes. They will all be covered below.

Traits

Legendary Resistance (3/Day): The ancient blue dragon can choose to succeed even if it fails a saving throw.

Actions

Multiattack: Actually, this multiattack allowed the ancient dragon to use its Frightful Presence. The dragon then attacks with its bite and its claws, as well as two additional times.

Take a bite: The bite attack can be used by the monster to create a Melee weapon attack. It is +16 to hit, reach 15, ft. and one target. Also Hit: 20 (2d10 + 9) piercing damage plus 11 (2d10) lightning damage.

ClawUsing the claw, the dnd old blue dragon can create Melee Weapon Attack. +16 to hit, reach 10 feet., one target. Hit: 16 (2d6 + 9) slashing damage.

Tail: Melee weapon attack: +16 to hit. Hit 20ft. one target. Hit: 18 (2d8+9) bludgeoning.

Frightful Presence: Each and every creature of a blue Dragon 5e choice within 120 feet must succeed on the DC 20 Wisdom saving Throw or it should be frightened for a moment. If a creature is able make a saving throw at the end each turn, it must also be able end any effect it has on others. Consider this: If the creature’s save throw is successful, or otherwise the effect would be ended for it.

Lightning Breath (Recharge 5-6)Basically, the d&d5e ancient blue dragon is able to exhale fire lightning in a 120-foot line that is 10 feet wide. Every creature within that line must make a DC 23 Dxterity saving throw. Even if they fail, they can take 88 (16d10) lightning damages, or half the damage if they succeed.

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Legendary Actions

According to the dungeons and dragons monsters the 5e old dragon can perform three legendary acts. Choose from the following options. You can only use one legendary action at a time. You can redeem the legendary Actions that have been spent at the end of each turn.

Detect: The Wisdom (Perception), check is made by the d&d old blue dragon.

Tail Attack: A tail Attack is made by the d&d ancient dragon.

Wing Attack (Costs two Actions): The d&d ancient dragon can beat its wings naturally. All creatures within the 15ft. range of a dragon need to succeed on a DC 24 Decterity saving throw. If it fails, it will take 16 (2d6 + 9) bludgeoning damage and be forced to prone. The speed of an ancient blue dragon in d&d is half.

Attributes Of DnD 5E Ancient Blue Dragon

AC 22 (Natural Armor).
Alignment Lawful Evil
CHA 21
CON 27
Challenge Rating 23
DEX 10
HP 481 (26d20+208).
INT 18
Immunities Lightning
Languages Draconic, Common
Passive Perception 27
Roll 0 Enjoy 1d20 + 162d10+9+2d10
Roll 1 Claw 1d20 + 162d6+9
Roll 2 Tail 1d20 + 16 4d8+9
Roll 3 Lightning Breath 1d20 + 0 16d10
STR 29
Throws to Save Dex +7; Con +15; Wis +10; Cha +12
Senses Blindsight 60 ft., Darkvision 120 ft.
Size Gargantuan
Skills Stealth +7, Perception +17
Speed 40 ft. Burrow 40 ft. Fly 80 ft.
Type dragon
WIS 17