Amber Golem

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.

Multiattack. The golem makes two slam attacks.

Slam. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 18 (3d8 + 5) bludgeoning damage.

Static Charge (Recharge 5–6). The golem targets one creature it can see within 10 feet of it. Each target must make a DC 16 Strength saving throw against this magic. On a failed save, an item held by the affected creature is pulled from their hand and sticks to the golem's body. On a successful save, randomly determine an object not held or worn by the creature, that sticks to the golem's body instead. Stuck objects can be removed with a DC 16 Strength (Athletics) check. When the golem reaches 0HP, all objects still stuck to its body are released.

Capacitance. Whenever the golem takes Lightning damage, that energy is "stored" within its body. As a Free Action on its turn, the golem may either release this energy in an Aura affect, dividing the amount stored equally among each creature within 10 feet (rounding down), or deal the entire amount to one creature it hits with a single Slam attack. In the latter case, the damage is not dealt twice if both Slam attacks hit. As long as the golem has not released this charge, it stays inside the golem's body, and increases accordingly the more Lightning damage it takes. If the golem reaches 0 HP before releasing the charge, it explodes out and shatters the golem's body, dealing whatever Lightning damage remains as well as 3d6 Piercing damage to any creatures within 10 feet from the shrapnel. A DC 16 Dexterity saving throw halves the Piercing damage, but not the Lightning damage.