Calderus, Father of Giants

Legendary Resistance (3/Day). If the titan fails a savings throw is can choose to succeed instead.

Innate Spellcasting. The Titan's spellcasting ability is [charisma] (spell save DC 20.) The Titan can innately cast the following spells, requiring no material components:

At Will: Command, Thaumaturgy, Bless (7th Level), Bane (7th Level), Hold Person

2/day: Dominate Person, Telekinesis, Suggestion, Fear, Hold Person (4th Level)

1/day: Dominate Monster, Chain Lightning, Fire Storm, Power Word Stun

Titanic Bronze: Calderus is coated in Titanic Bronze, a godly material that offers him great protection and power until it has been broken. While Calderus has more than 150 hit point he has the following benefits:

Calderus' weapon attacks are magical.

Calderus has advantage on saving throws against spells or other magical effects.

Calderus' AC is 24.

Calderus is resistant to magical bludgeoning, piercing, and slashing damage; as well as cold, fire, lightning, thunder, and necrocitc damage.

Once Calderus' hit points are reduced below 150 he losses these benefits and cannot regain them until armor is repaired. Healing above 150 does not repair armor

Multiattack. Calderus can make 3 melee attacks

Adamantine Maul Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 38 (8d6 + 10) Bludgeoning damage. 

Titanic Strike. Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit: 35 (6d10 + 8) Bludgeoning damage. 

Eye of Balor (Recharge 5-6). Calderus unleashes the Eye of Balors raw destructive power in a line 300ft long and 10ft wide, each creature in this line must make a DC 20 Dexterity saving throw or take 8d12 Radiant damage plus 8d12 Fire damage. The beam deals maximum damage to any structure it hits.

Change Shape. The titan magically polymorphs into a humanoid or beast that has a challenge rating no higher than its own, or back into its true form. It reverts to its true form if it dies. Any equipment it is wearing or carrying is absorbed or borne by the new form (the titan's choice).

In a new form, the titan retains its alignment, hit points, Hit Dice, ability to speak, proficiencies, Legendary Resistance, and Intelligence, Wisdom, and Charisma scores, as well as this action. Its statistics and capabilities are otherwise replaced by those of the new form, except any class features or legendary actions of that form.

The monster can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The monster regains spent legendary actions at the start of its turn

Melee Strike (Costs 1 Action). Calderus takes one melee attack action.

Titanic Leap (Costs 1 Action). Calderus leaps to a location within 25ft of him.

Impose Will (Costs 2 Actions). Calderus uses one of his At Will spells.