Castle Golem

Immutable Form: The Castle Golem is immune to any spell or effect that would alter its form.

Magical Resistance: The Castle Golem has advantage on saving throws against spells and other magical effects.

Siege Monster: The Castle Golem does double damage to objects and structures.

False Appearance. While the Castle Golem remains motionless, it is indistinguishable from a large keep or castle (+5 to stealth checks)

Multiattack: The Castle Golem can use its both its Fling and Slam attacks.

Fling: Ranged Weapon Attack +16 to hit, range 60/180 ft., one target. Hit: 55 (10d10) bludgeoning damage. If the target is a creature, it must succeed on a DC20 Strength saving throw or be knocked prone.

Slam: Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 75 (12d10+7) bludgeoning damage.

Rock: Ranged Weapon Attack: +16 to hit, range 60/180 ft., one target. Hit: 80 (15d10) bludgeoning damage.

Stone Shield: When the Castle Golem is hit by a melee weapon attack, it can use its reaction to deflect the attack. The Castle Golem takes no damage from the attack, and the attacker must succeed on a DC20 Strength saving throw or be knocked prone.

The Castle Golem can take 4 legendary actions, choosing from the options below. Only one legendary action may be used at a time and at the end of another creatures turn. The Castle Golem regains 1d4 legendary actions at the start of its turn.

Thunderous Stomp (Costs 1 Action). The Castle Golem slams its foot onto the ground, creating a shockwave the extends out to a radius of 30 feet. Each creature within that area must make a DC 20 Strength saving throw, taking 44 (8d10) thunder damage on a failed save, or half as much damage on a successful one. Any unsecured objects that are in the area of effect are automatically pushed 10 feet away from the Castle Golem.

Shove (Costs 2 Actions). The Castle Golem moves up to half its movement speed and makes one Slam attack against a creature it moves adjacent to.

Rock Throw (Costs 2 Actions). The Castle Golem hurls a rock at a point it can see within 60 feet of it. Each creature within 10 feet of that point must make a DC20 Dexterity saving throw, taking 44(8d10) bludgeoning damage on a failed save, or half as much on a successful one.