Adult lightning Ape

Lightning fur:  The Lightning ape emits a 30ft dim light from the electrical charge emitted from  its fur.  this provides resistance to lightning damage. 

Electrically charged (five times per day):  As a bonus action the lightning ape can become further electrically charged . While electrically charged the creature has immunity to lighting damage and their melee attacks deal additional lighting damage. 

If electrically charged and the creature uses the Lighting blast  legendary action creatures that are caught in the stream make the dex save at disadvantage ( conditions that provide advantage cancel this ability out). After using Lighting blast  roll a D20. any role under 12 and the Electrically charged  state ends and cant be used again until the start of the third turn from when it ended. 

Enraged:  As a bonus action The Lightning ape may become increasingly angry . While in this state the Lighting ape becomes resistant to all weapon based attacks ( magical or otherwise) for up to one minute. Additionally the Lightning apes attacks become more violent dealing additional damage. 

The lightning ape may use this feature while electrically charged. 

Legendary resistance 3/day  

Multiattack. The ape makes Three fist attacks.

Fist. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 9 (1d6 + 6) bludgeoning damage + 3 (1d6) Lightning damage. When Electrically charged, The attacks deal an additional 2d6 lightning damage. When Enraged,  The attacks deal an additional 2d6 bludgeoning damage.  

Rock. Ranged Weapon Attack: +8 to hit, range 100/200 ft., one target. Hit: 15 (3d6 + 6) bludgeoning damage. When Electrically charged, The attacks deal an additional 2d6 lightning damage. When Enraged,  The attacks deal an additional 2d6 bludgeoning damage.  

As a reaction the Lightning ape may use it's reaction to grapple a player DC: 18 athletics or acrobatics to escape.  

The lightning ape may take up to 3 legendary actions before the start of its next turn. 

(Recharge 4-6) Lightning blast (1 action) :  Range:  45 ft x 5 ft: DEX SAVE DC 18  : failed save take  15 (5d6) lightning Damage or half as much on a successful save.  While Electrically charged  This attack deals an additional 3d6 lightning damage   

Frightful Presence (1 action)  : DC 18 wis save  or come under the condition of the Fear condition. The creature who is under this condition the creature cannot willining approach the creature and has disadvantage on all attacks made to the creature. Passing the save make you immune to this effect for 24 hours. 

Electric infusion (2 actions): while grappled the creature must make a DC 18 con save or take 12 (4d6) lightning damage or half if passed. If the player is wearing metal that player becomes electrically charged. While electrically charged the Lightning ape may use it's Rock throw to throw the creature. A small to medium creature thrown this way deals an additional 2d6 +6 bludgeoning to its self and the target  and 5d6 lightning damage to the target but not the creature thrown. A large creature deals 6d6 +6 bludgeoning to both and 8d6 lightning damage. to the target.

While the creature has metal items infused with electricity on: Their movement is halved (rounded up) they have disadvantage on all dex and strength based  attacks and saving throws. This effect lasts up until the end of the creatures 3rd turn or if thrown at a creature or if they are able to hit a creature with the electrically infused item ( dealing the lighting damage to that creature).