Clockwork Construct

Berserk. Whenever the golem starts its turn with 40 hit points or fewer, roll a d6. On a 6, the golem goes berserk. On each of its turns while berserk, the golem attacks the nearest creature it can see. If no creature is near enough to move to and attack, the golem attacks an object, with preference for an object smaller than itself. Once the golem goes berserk, it continues to do so until it is destroyed or regains all its hit points

Aversion of Fire. If the golem takes fire damage, it has disadvantage on attack rolls and ability checks until the end of its next turn.

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

Lightning Absorption. Whenever the golem is subjected to lightning damage, it takes no damage and instead regains a number of hit points equal to the lightning damage dealt.

Alacrity: Once per round, the Golem may take an extra standard action (either before or after its other actions in the round).

Insight: The Golem has a general idea of what action it might take to best protect itself and gives it a +2 insight bonus to AC and Reflex saves. This insight bonus is lost whenever it would lose a Dexterity bonus to AC.

Multiattack. The golem makes two slam attacks.

Slam. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage.

Agony Shift: (Will: half; Crit: status effects) The fabric of time parts to the Golem's will, revealing wounds/effects you have received in the past (or has yet to receive). That foe takes 2d6 points of damage as the past (or future) impinges briefly on the present.

Gaze: The clockwork eyes of the Golem radiate time-manipulating magics. The Golem can fix its gaze on a target(s) in a 6-foot cone. Targets must pass a CHA save or suffer -1 to saves due to fear (Intimidation automatically saves). Golem may continue to roll for gaze effects until distracted from target by damage/etc, or target is removed from AoE.

Lagging Gaze: The gaze from the Golem makes the target seem to start moving at a different speed than the rest of the world. Opponents in a 6-foot cone must succeed on a DC 17 Will save or be affected as though by a slow spell for 1d6 rounds. The save DC is Charisma-based. Crit: Time Stop (lose 1d4 turns).

Eternity Gaze: the Speeding clock is fixed on you, in a 6-foot cone. Make a DEX save; failing that, you are affected by Weakness (1d6 damage to STR and DEX, disadvantage on all rolls) for 1d4 turns. Crit: your weapons and armor age to dust.