Fellforged

Medium Construct Lawful Evil

STR	DEX	CON	INT	WIS	CHA
14 (+2)	12 (+1)	17 (+3)	12 (+1)	14 (+2)	15 (+2)

Saving Throws: Str +5, Wis +5
Skills:
Damage Vulnerabilities: False
Damage Immunities: necrotic, poison, psychic
Damage Resistances: acid, cold, fire, lightning
Condition Immunities: charmed, exhaustion, frightened, paralyzed, petrified, poisoned
Senses: darkvision 60 ft., passive Perception 12
Languages: the languages it knew in life

Construct Nature: The fellforged doesn't require air, food, drink, or sleep.
Inhabiting Spirit: The fellforged is inhabited and animated by a specter. If the fellforged fails a saving throw against an effect that turns undead, the specter is expelled into an unoccupied space within 5 feet of the fellforged with the hp total it had before it was expelled. The specter otherwise uses the statistics of a specter.
Sunlight Sensitivity: While in sunlight, the fellforged has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.

Multiattack: The fellforged makes two Necrotic Slam attacks.
Necrotic Slam: Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 9 (2d6 + 2) bludgeoning damage plus 9 (2d8) necrotic damage. If the target is a creature, it must succeed on a DC 14 Constitution saving throw or its hp maximum is reduced by an amount equal to the necrotic damage taken. This reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hp maximum to 0.

Burst Gears: The specter within the fellforged strains the construct's body, sending broken springs and gears flying. Each creature within 5 feet of the fellforged must make a DC 14 Dexterity saving throw, taking 7 (2d6) piercing damage on a failed save, or half as much damage on a successful one. Each time the fellforged uses this bonus action, its speed is reduced by 5 feet, and it can't use this bonus action if its speed is 0. Its speed returns to normal when it finishes a long rest.