Medium construct, unaligned

Armor Class: 16 (natural armor)

Hit Points: 58 (9d8 + 18) 9d8+18

Speed: 30 ft

STR

12 +1

DEX

18 +4

CON

15 +2

INT

3 -4

WIS

10 +0

CHA

1 -5

Damage Immunities: poison; bludgeoning, piercing, and slashing from nonmagical attacks that aren't adamantine

Condition Immunities: charmed, exhaustion, frightened, paralyzed, petrified, poisoned

Senses: darkvision 60 ft., passive Perception 10

Languages: understands one language of its creator but can't speak

Challenge Rating: 5

Walking Ballista by Daniel Ljunggren

Actions

Multiattack. The walking ballista makes two lancing bolt attacks or one lancing bolt attack and one harpoon attack.   Lancing Bolt. Melee or Ranged Weapon Attack: +7 to hit, reach 5 ft. or range 100/400 ft., one target. Hit: 15 (2d10 + 4) 2d10+4 piercing damage.   Harpoon. Ranged Weapon Attack: +7 to hit, range 50/200 ft., one target. Hit: 9 (1d10 + 4) 1d10+4 piercing damage, and the target is grappled (escape DC 12). While grappled in this way, a creature's speed isn't reduced, but it can move only in directions that bring it closer to the walking ballista. A creature takes 5 (1d10) 5d10 slashing damage if it escapes from the grapple or if it tries and fails. As a bonus action, the walking ballista can pull a creature grappled by it 20 feet closer. The walking ballista can grapple only one creature at a time.   Explosive Bolt (Recharge 5–6). The walking ballista launches an explosive charge at a point within 120 feet. Each creature within 20 feet of that point must make a DC 15 Dexterity saving throw, taking 17 (5d6) fire damage on a failed save, or half as much damage on a successful one.