Inspired by the Terrible Iron Golem from Maure Castle I decided to make my own version for my campaign setting and set him as a defender of The Choking Tower. My players bypassed him so will use this little surprise again. Slightly modified of course.
THE TERRIBLE IRON GIANT
Large construct, unaligned
Armor Class 20 (natural armor)
Hit Points 210 (20d10 + 100)
Speed 30 ft.
Initiative Speed -3 (Dex -1, large -2)
STR 24 (+7) DEX 9 (-1) CON 20 (+5)
INT 3 (-4) WIS 11 (+0) CHA 1 (-5)
Damage Resistances bludgeoning, piercing, and slashing
Damage Immunities fire, poison, psychic; bludgeoning, piercing, and slashing from nonmagical weapons that aren’t adamantine
Condition Immunities charmed, exhaustion, frightened, paralyzed, petrified, poisoned
Senses darkvision 120ft., passive Perception 10
Languages understands Gothic but can’t speak
Challenge 16 (15,000 XP)
Fire Absorption. Whenever the golem is subjected to fire damage, it takes no damage and instead regains a number of hit points equal to the fire damage dealt.
Immutable Form. The Terrible Iron Giant is immune to any spell or effect that would alter its form.
Magic Resistance. The Terrible Iron Giant has advantage on saving throws against spells and other magical effects.
Magic Weapons. The Terrible Iron Giant’s weapon attacks are magical.
Thickened Sculpture. The Terrible Iron Giant has resistance against bludgeoning, piercing, and slashing damage when magical or adamantine weapons bypass immunity. Only construct bane weapons fully bypass damage immunities and resistances.
Multiattack. The Terrible Iron Giant makes two melee attacks.
Cockatrice Feather Whip. Melee Weapon Attack: +13 to hit, reach 5 ft., one target.
Hit: 20 (3d8 + 7) slashing damage, damage, and the target must succeed on a DC 18 Constitution saving throw against being magically petrified. On a failed save, the creature begins to turn to stone and is restrained. It must repeat the saving throw at the end of its next turn. On a success, the effect ends. On a failure, the creature is petrified for 24 hours.
Thunder Hammer. Melee Weapon Attack: +13 to hit, reach 10 ft., one target.
Hit: 23 (3d10 + 7) lightning damage.
Fire Breath (Recharge 6). The golem exhales a blast of fire in a 15-foot cone. Each creature in that area must make a DC 18 Constitution saving throw, taking 45 (10d8) fire damage on a failed save, or half as much damage on a successful one.
This massive iron statue sits upon an impressive granite throne. It has been carved to look like a titanic gearsmen but is clearly a finely crafted sculpture. It holds an immense crystal sword in its left hand and a whip of long, broad, interwoven feathers in its right hand.