Azdaha

Legendary Resistance (3/Day). If Azdaha fails a saving throw, he can choose to succeed instead. When he does, his sight, Blindsight, and Truesight are reduced to a range of 30 feet until the start of his next turn.

Storm of the Gods. Lightning and Thunder damage dealt by Azdaha ignore damage Resistance.

Multiattack. Azdaha makes one Bite attack and two Claw attacks.

Bite. Melee Attack Roll: +16, reach 15 ft. Hit: 20 (2d10 + 9) Piercing damage plus 5 (1d10) Lightning damage, and Azdaha can move the target up to 20 feet in any direction.

Claw. Melee Weapon Attack: +16, reach 10 ft. Hit: 16 (2d6 + 9) Slashing damage plus 7 (2d6) Thunder damage, and the target is knocked Prone.

Lightning Breath (Recharge 5–6). Dexterity Saving Throw: DC 23, each creature in a 120-foot-long, 30-foot-wide Line. Failure: 66 (12d10) Lightning damage, and the target has Disadvantage on saving throws until the end of Azdaha's next turn. Success: Half damage only.

Lightning Discharge. Azdaha makes a Bite attack. On a hit, Azdaha's teeth spark with energy, dealing an extra 11 (2d10) Lightning damage to the target and to one other enemy within 60 feet of the target.

Voice of Negation. Trigger: A creature Azdaha can see within 60 feet of him uses an action or Bonus Action to cast a spell. Response -- Spell Saving Throw: DC 23 (saving throw made with target's Spellcasting ability). Failure: 16 (3d10) Thunder damage, and the target is unable to cast spells until the end of its turn, but the spell slot is not expended and the creature’s action is not lost.

Azdaha has three Villain Actions. He can take each action once during an encounter after an enemy’s turn. He can take these actions in any order but can use only one per round.

Voice of Reverence. Wisdom Saving Throw: DC 20, each creature of Azdaha's choice within 60 feet of Azdaha. Failure: The target falls Prone. A creature who falls Prone in this way takes 22 (4d10) Thunder damage if it stands up before the end of Azdaha's next turn.

Fulguration. Azdaha sheds his physical form to become a being of energy until the end of his next turn. While in this form, Azdaha gains the following benefits: 

• He has Resistance to all damage.
• He can move through a space as narrow as 1 inch wide without squeezing.
• His movement doesn’t provoke Opportunity Attacks.
• He can move through any creature’s space, and when he moves into a creature’s space for the first time on a turn, that creature takes 16 (3d10) Lightning damage.

Voice of the Ages. Wisdom Saving Throw: DC 20, each enemy within 60 feet of Azdaha who can hear him. First Failure: 44 (8d10) Psychic damage, and the target falls Prone and is unable to stand up as it weeps uncontrollably. The target repeats this saving throw at the end of each of its turns. Subsequent Failures: The target remains unable to stand up. Success: Half damage only. The target automatically succeeds after 1 minute.