Sources
CR
Type
Size
Alignment
Movement

Headless Iron Golem

Large Construct, Unaligned

Armor Class 20 (natural armor)
Hit Points 150 (10d10 + 50)
Speed 30 ft.
STR
24
+7
DEX
9
-1
CON
20
+5
INT
3
-4
WIS
11
+0
CHA
1
-5
Damage Immunities fire, poison, psychic; bludgeoning, piercing, slashing, from nonmagical attacks that aren't adamantine
Condition Immunities Charmed, Exhaustion, Frightened, Paralyzed, Petrified, Poisoned
Senses darkvision 120 ft., passive Perception 10
Languages understands the languages of its creator but can't speak
Challenge 10 (5,900 XP)

Traits

Headless. The golem is blinded and deafened, giving it disadvantage on all its attack rolls, and it can't use its Poison Breath.

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 golem is immune to any spell or effect that would alter its form.

Magic Resistance. The golem has advantage on saving throws against spells and other magical effects.

Magic Weapons. The golem's weapon attacks are magical.

Actions

Multiattack. The golem makes two melee attacks.

Slam. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit:20 (3d8 + 7) bludgeoning damage.

Sword. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit:23 (3d10 + 7) slashing damage.

Lore

The mightiest of the golems, the iron golem is a massive, towering giant wrought of heavy metal. An iron golem's shape can be worked into any form, though most are fashioned to look like giant suits of armor. Its fist can destroy creatures with a single blow, and its clanging steps shake the earth beneath its feet. Iron golems wield enormous blades to extend their reach, and all can belch clouds of deadly poison.