Corrupted Crystal 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.

Illumination. The golem magically sheds bright light in a 30-foot radius and dim light for an additional 30 feet. This light goes out when the golem is destroyed.

Light Intensity. Any creature that starts its turn within 10 feet of the illuminated golem and can see the golem must succeed on a DC 17 Wisdom saving throw or be blinded until the start of the creature’s next turn.

A creature can avert its eyes to avoid the saving throw at the start of its turn. If the creature does so, it can’t see the golem until the start of its next turn, when it can avert its eyes again. If the creature looks at the golem in the meantime, it must immediately make the save.

Multiattack. The golem makes two slam attacks.

Slam. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 19 (3d8 + 6) bludgeoning damage. The target must succeed on a DC 13 Constitution saving throw or its hit point maximum is reduced by an amount equal to half the damage taken. This reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0. If the target is humanoid, the golem regains hit points equal to the number of hit points lost.

Crystal shards. The golem fires crystal shards at a point within 30 ft. The ground in a 5-foot radius becomes covered in sharp crystal shards and the golem's hit point maximum is decreased by 1d10. The area becomes difficult terrain for the duration. When a creature moves into or within the area, it takes 2d4 piercing damage for every 5 feet it travels.

Anyone that takes damage from this ability must succeed on a DC 13 Constitution saving throw or its hit point maximum is reduced by an amount equal to half the damage taken. This reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0. If the target is humanoid, the golem regains hit points equal to the number of hit points lost.