Alpha Titan: Ghidorah

Alien. Does not need to breath oxygen. 

Alpha Titan. He can command other Titans, except for other Alpha Titans. 

Regeneration. Ghidorah heals 30 hp per round, and will even regrow body parts.

Electrical Aura. Supercharges the air, causing a perpetual storm to surround Ghidorah. Lightning has 1/6 chance to hit anyone at the start of their turn in the storm, dealing 10d10 lightning damage. However it costs him 1 stored energy per round to maintain. When he sleeps he has a storm that surrounds him constantly and charges up his stored energy, so that he wakes up with a full amount.

Multiple Heads. The Ghidorah has three heads. While it has more than one head, it has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

Reactive Heads. For each head Ghidorah has beyond one, it gets an extra reaction that can be used only for opportunity attacks.

Wakeful. While the Ghidorah sleeps, at least one of its heads is awake.

Bio-Eletrical Nature. He conducts electrical currents and absorbes lightning damage. He can used that energy to heal himself, or to charge his attacks. He can have maximum stored energy as much as his max hp amount. Ghidorah will usually start with a full amount of stored energy at the beginning of a fight.

Legendary Resistance (3/Day). If Ghidorah fails a saving throw, it can choose to succeed instead.

Titan Power. Ghidorahs attacks count as magical to overcome resistances.

Frightening Rattle. Ghidorah rattles his tails and forces everyone that hears it, to make a dc 20 charisma save or be scared of Ghidorah. Feared targets can repeat the save at the end of their turn, ending the condition on a success. After succeeding the saving throw a creature is immune to the rattle.

Multiattack. Each head attacks with one Bite Attack or one Gravity Breath. Alternatively Ghidorah attacks with two tail attacks. 

Bite Attack. Melee Attack: +15 to hit, reach 50 ft., 1 target. Hit: 30 (2d10 + 20) [piercing] damage. 

Gravity Breath. Ranged Attack: any creature in a 10x600 line musst make a dc 22 dexterity check or take 40 (4d10+ 20) [lightning] damage. For every energy charge used for the attack, the damage is increased by 1. Stored energy applied is also applied to all other gravity breath attacks.

Tail Attack. Melee Attack: +20 to hit, reach 100 ft., 1 target. Hit: 15 (1d10+10) [bludgeoning] damage. A target hit by this attack is automatically grappled and must use it's action to make a DC 24 strength saving throw to free itself.

Heal. Use stored energy to recover hp. 

Beamlock. If Ghidorah is targeted by a line aoe attack, he can make a breath attack to counter it, but he cannot make a dex or Con save to evade it. Instead Ghidorah subtracts the amount of damage received with the damage of Ghidorahs Gravity Beam. 

Ghidorah 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. Ghidorah regains spent legendary actions at the start of its turn.

Triple Attack (Costs 1 Actions). Ghidorah makes three bite attacks on a target in range.