Legendary Resistance (3/day). If the Golem Fails a saving throw, it can choose to succeed instead

Immutable form. The Golem is immune to any spell or effect that would change its form.

Magic weapons. The Golems weapon attacks count as magical.

Reactive. The Golem can take a reaction on every turn in a combat.

Immunity Absorbtion. When the golem receives damage from a source it is immune to it heals for the damage amount instead.

Multi-Attack. The golem makes three slam attacks. the golem can replace one of its attacks with its resistance retaliation and its Star Radiance.

Slam Attack.  Melee Weapon Attack: +9 to hit, reach 10 ft., 1 target. Hit: 31 (4d10 + 5) [Bludgeoning] damage.

Resistance Retaliation. The Golem releases one of the resistance energies that it has built up and sheds that resistance. When it does so, it releases an attack based on the resistance that it chose to shed, which does one of the following.

Slashing Damage. A large blade flips out from its arm and adds 26 (4d10) [slashing] damage to the Slam Attack if it hits.

Piercing Damage. A bolt shoots from the palm Ranged Weapon Attack: +9 to hit, range 60/120 ft., 1 target. Hit: 18 (4d8 + 5) [Piercing] damage. On a hit the target must then make a (DC18) Strength saving throw to avoid being pinned to the floor (Grappled) by the bolt.

Bludgeoning Damage. The Golem brings both hands together and forms a sledgehammer that adds 31(4d10+5) [Bludgeoning] Damage to the Slam Attack if it hits.

Acid Damage.  A nozzle appears from the Golems mouth, and it releases a stream of acid 60 ft long and 10 ft wide. all creatures in its path must make a (DC18) Dexterity saving throw or take 24 (6d6) Acid Damage on a failed save or half on a save.

Cold Damage. A blast of cold erupts from the Golems hands in a 60ft cone Each creature in the area must make a (DC18) Constitution saving throw or take 50 (10d10) Cold Damage on a failure or half damage on a save.

Fire Damage. Fire shoots out from both its palms as the Golem raises both arms to its sides and its top half rotates rapidly. Each other creature in a 30 ft Radius must make a (DC 18) Dexterity saving throw or take 40 (10d6) Fire Damage on a failure or half as much on a save.

Force Damage. The Golem slams the ground with both hands sending out a wave of force energy through the ground Each creature in a 60 ft cone must make a (DC18) Strength saving throw or take 44 (8d10) Force Damage and be pushed back 15 ft and knocked prone on a failure or half as much damage and not pushed back or knocked prone.

Lightning Damage. The Golem releases a stream of red lightning from its eyes 100 ft long and 10 ft wide. Each creature in the path must make a (DC 18) Dexterity saving throw or take 50 (10d8) Lightning Damage on a failure and half as much on a save.

Thunder Damage. The Golem slams both of its hands together releasing a shock wave in a 20 ft radius. Each other creature in the area must make a (DC18) Strength saving throw or take 40 (8d8) Thunder Damage and are pushed 10 ft away from the Golem on a failure or half as much damage and are not pushed away on a save.

Necrotic Damage. The Golem makes a Slam Attack and on a hit the Golem Deals an extra 42(6d12) Necrotic Damage. and heals for the damage delt.

 Radiant Damage. The Golem releases a blindingly bright flash of light in a 30 ft radius. all other creatures in the area must make a (DC18) Constitution Saving throw or be blinded for one minute and take 42 (7d10) on a failure or not blinded and half damage on a save. a creature that has been blinded can repeat the saving throw on the end of its turns to end the effect early.

Star Radiance (Recharges on a 5-6). The Golem opens its armor revealing its core pulsing with all the damage types it has built up immunities to so far, sending out radiant light in a 60 ft radius. All other creatures in the area must make a (DC18) Charisma saving throw or take 45 (8d10+5) Radiant Damage + an additional 6 (1+10) Radiant Damage per immunity it has built up, after which the Golems Immunities are changed back to resistances.

Adaptable Resistances. When the Golem receives damage that it's not resistant or immune to it can use its reaction to become resistant to that damage type (thunder, acid, piercing damage from a magic weapon, ext.).

Adaptable Immunities. When the Golem receives damage from a source that it's resistant to it can use its reaction to become immune to that damage type. 

The Golem can take 3 legendary actions, choosing form the options below. Only one legendary action can be used at a time and only at the end of another creatures turn. The golem regains spent legendary actions at the start of the turn.

Slam Attack. The Golem Makes a slam attack.

Resistance Retaliation (Cost 2 Actions). The Golem uses one of its Resistance Retaliation abilities.