Clay Golem

Clay Golem CR: 9

Large construct, neutral

Armor Class: 14 (natural armour)

Hit Points: 133 14d10+56

Speed: 20 ft

STR

20 +5

DEX

9 -1

CON

18 +4

INT

3 -4

WIS

8 -1

CHA

1 -5

Damage Immunities: Acid, Poison, Psychic, Bludgeoning, Piercing, and Slashing attacks made with nonmagical weapons not made with adamantine

Condition Immunities: Charmed, Exhaustion, Frightened, Paralyzed, Petrified, Poisoned

Senses: Darkvision 60 ft, passive Perception 9

Languages: Understands the languages of it's creator but can't speak

Challenge Rating: 9

Acid Absorption. Whenever the golem is subjected to acid damage, it takes no damage and instead regains a number of hit points equal to the acid damage dealt.
Berserk. Whenever the golem starts it's turn with 60 hit points or lower, roll a d6 1d6 . On a 4-6, the golem goes berserk. On each of the turns while berserk, the golem attacks the nearest creature it can see. If no creature is near enough to to move to and attack, the golem attacks an object, with preference to objects smaller than itself. Once the golem goes berserk, it continues to do so until it is destroyed or regains all it's hit points.
Immutable Form. The golem is immune to any spell or effect that would alter it's 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 slam attacks.
Slam. Melee Weapon Attack +8 to hit, reach 5 ft, one target. Hit 16 2d10+3 bludgeoning damage. If the target is a creature, it must succeed on a DC 15 Constitution saving throw or have it's hit point maximum reduced by an amount equal to the damage taken. The target dies if this attack reduces it's hit points maximum to 0. The reduction lasts until removed by the Greater Restoration spell or other magic.
Haste (Recharge 5-6). Until the end of the next turn, the golem magically gains +2 to it's AC, has advantage on Dexterity saving throws, and can use it's slam attack as a bonus action.

Clay golems are fashioned out of clay in a rough humanoid shape. Like many golems they are taller than most medium sized humanoids. Most clay golems are created by priests who look upon such creatures as protectors of their people.