Colossal Stone Guardian

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

Immutable Form. The Colossal Stone Guardian is immune to any spell or effect that would alter its form. 

Colossal Size: The Colossal Stone Guardian is colossal, it ocupies a 40ft wide 40ft long 140ft tall space.

Mind Control Imunity; The Colossal Stone Guardian is immune to effects that would force it to act agaisnt its  established program (will).

Magic Resistance. The Colossal Stone Guardian is immune to spells cast with spell slots of 5th level or lower and has advantage on saving throws against spells and other magical effects.

Weak Balance: The Colossal Stone Guardian impressive size is its most powerful asset however it is also its most glaring weakness, it has disadvantage on saving throws to avoid the prone condition, furthermore it must use its full action to stand up from the prone condition. (You may make the Colossal Stone Guardian imune to the prone condition falling only when it dies.)

Fall of the Colossus: Whenever the Colossal Stone Guardian falls prone, all creatures and structures within 90ft of the Colossal Stone Guardian must succeed in a DC 25 Dexterity saving throw taking 12d12 bludgeoning damage being pushed back 15ft and falling prone on a failure, half damage on a success and no additional effects. (You may choose to only use this feature once the Colossal Stone Guardian falls to 0 hit points.)

Seige Monster: The Colossal Stone Guardian deals double damage to structures.

Magic Weapons. The Colossal Stone Guardian's weapon attacks are magical.

Moving Mountain: The Colossal Stone Guardian is immune to any speed reduction other than from spells cast with spell slots of 8th level or higher.

Immeasurable Weight: The Colossal Stone Guardian is massivly heavy and not particulary agile, it cannot swim nor jump or use the dash action, however it can walk normaly across the ground of bodies of water or other liquids, additionaly it cannot be moved agaisnt its will other than from spells cast with spell slots of 8th level or higher.

Colossus Fortitude The Colossal Stone Guardian only takes damage if the attack deals 15 damage or more (this is calculated after resistances).

Colossal Grasp:All creatures within a 10ft cube within 35ft of the Colossal Stone Guardian must succeed in a DC 18 Dexterity saving throw, on a failure they take 12d10+12 bludgeoning damage and are restrained by the hand of the Colossal Stone Guardian, a creature can as an action atempt to succeed in a DC 26 Strenght saving throw to escape the restraining hand, tiny and gargantuan creatures cannot be restrain by the Colossus graps, however they still take damage.
All creatures hit by the attack that can be restrained by it and are within the targeted area are restrained in one of the Colossal Stone Guardian´s hands.
The Colossal Stone Guardian can only perform this attack if it has at least one free hand.

Colossal Stomp: All Creatures within 60ft of the Colossal Stone Guardian must succeed in a DC 18 Dexterity saving throw taking 6d12+6 thunder damage + 6d12+6 bludgeonig damage and falling prone on a failure half as much damage on a success and no additonal effects.

Smash Ant: Melee Weapon Attack; +18 to hit, 35ft range, one target, 6d12+8 Bludgeoning damage, a creature large or smaller hit by this attack falls prone and has their bones crushed with their speed reduced by half until it heals at least 10hp, creatures with no bones or otherwise unphased by broken bones are immune to this effect.
The Colossal Stone Guardian can only perform this attack if it has at least one free hand.

Crushing Grasp: As a bonus action the Colossal Stone Guardian can crush whatever creatures restrained by its Colossal Grasp, all restrained creatures take 6d12+6 bludgeonig damage,