Converted for The Choking Tower. My group bypassed him however.
ANIMATED CRANE
Large construct, unaligned
Armour Class 17 (glaucite)
Hit Points 178 (17d10 + 85)
Speed 0 ft. (immobile)
STR 22 (+6) DEX 8 (-2) CON 20 (+5)
INT 1 (-5) WIS 1 (-5) CHA 1 (-5)
Damage Immunities poison, psychic; bludgeoning, piercing, and slashing from non-magical weapons that aren’t adamantine
Condition Immunities charmed, exhaustion, frightened, paralyzed, petrified, poisoned
Senses darkvision 120ft., passive Perception 10
Languages understands Gothic but can’t speak
Challenge 8 (3,900 XP)
Immutable Form. The animated crane is immune to any spell or effect that would alter its form.
Magic Resistance. The animated crane has advantage on saving throws against spells and other magical effects.
Magic Weapons. The animated crane weapon attacks are magical
ACTIONS
Multiattack. The animated crane makes two slam attacks.
Slam. Melee Weapon Attack: +10 to hit, reach 30 ft., one target.
Hit: 19 (3d8 + 6) bludgeoning damage, and the target is grappled (escape DC 18). Until this grapple ends, the target is restrained. As bonus action the animated crane may drop a creature in to area F23.
TACTICS
During Combat The animated crane is immobile, but can strike at opponents with the claw at the end of its boom from anywhere in its reach. If it successfully grabs a creature, the crane swings its boom over the open space and drops the creature into area F23, 30 (3d6/18 bludgeoning) feet below.
Morale The animated crane fights until destroyed.