ancient golden hydra

Multi attack: it can use its fightful persistence to make five attacks per turn one with each head. 

Multi headed: it has advantage on saving throws against to being blind, charmed, defend frightened,

Stunted and knocked out. When it takes more than 104 damage in a turn it loses one of its heads if it loses all of its head it dies.

At the end of its turn it can use one of its turns to regrow all missing heads That died scien it last turn And it regains 50 hit points for each head regrown.

bioelectrical: it generated a storm around it self so

every opponents within 200 ft of it must make a dexterity saving throw if failed they are knocked into prone and tack 2d6 electrical damage. 

Reactive heads: for each head it has beyond one it gets an extra reaction for the opportune attack.

Legendary resistance: (3/day) if it fails a saving throw is 

Can, it can chose to succeed instead.   

Bite. melee weapon attack: 

+18 to hit, reach 60ft., 1 target. 

Hit: 3d10+12 piercing damage plus 4d6 electrical damage 

Claw. melee weapon attack: 

+17 to hit, reach 30ft., 1 target 

Hit: 2d6+10 piercing damage plus 4d6 electrical damage

Tail. melee weapon attack: 

+17 to hit, reach 120 ft 1+ target. 

Hit: 2d8+12 bludgeoning damage plus 4d6 electrical damage

Wing attack. 

Every opponent with in 60 ft must succeed in a 25 DC dexterity saving throw or take 2d6+10 bludgeoning damage and be knocked down into a prone position it can then fly up at half its flying speed..

Electrical breath (recharge 3 turns).

 It exhales lighting in

A 200ft line that is 10ft wide. Each creature in that line must make a DC 23 dexterity saving throw, taking 16d10 +4d6 

Lightning damage on a failed save, or half as much damage on a successful. 

Frightful presence. 

Each creature of its choice that is within 120 ft of it and aware Of it must succeed on a DC 21 wisdom saving throw

Or become frightened for 1 minute. A creature can repeat the saving throw at the end of its turn, ending the effects on itself on a success. If the creatures saving throw is successful the creature is immune from its frightful presence for the next 24 hours.

Legendary attacks

It has 3 legendary actions, choosing from the options below.

Only 1 legendary action can be used at a time and only at an others turn can it regain its lost legendary action point.  

Electrical blast.(cost 2 actions)

It create a aura of electromagnetic energy around itself and in a concussive force blast it outwards from its body everyone with in 100 ft of it must make a strength saving throw if failed then 6d6+10 electric damage is taken.

Summon electrical hurricane.(cost 3 actions)

It create a hurricane in the local area (120ft) each person in the area must make a dexterity saving throw if failed then will be knocked into the prone position. As well as a dexterity saving throw anyone in the area must also make a constitution saving throw in failed then they will take lightning damage 4d6 

Mental attack. (cost 4 actions)

It uses its telepathy to invade the opponent's mind and break them from the inside. 

It must make a intelligence saving throw and 

The victim must make a wisdom saving throw if the it has a higher number than the victim the victim becomes filled with fear and become delusional making every action have disadvantage for 5 turns.