Sources
CR
Type
Size
Alignment
Movement

Gearkeeper Construct

Large Construct, Unaligned

Armor Class 18 (natural armor)
Hit Points 161 (17d10 + 68)
Speed 60 ft.
STR
20
+5
DEX
16
+3
CON
18
+4
INT
3
-4
WIS
11
+0
CHA
1
-5
Damage Resistances bludgeoning, piercing, slashing, from nonmagical attacks
Damage Immunities fire, poison, psychic
Condition Immunities Charmed, Exhaustion, Frightened, Paralyzed, Petrified, Poisoned
Senses blindsight 120 ft., passive Perception 10
Languages understands the languages of its creator but can't speak
Challenge 10 (5,900 XP)

Traits

Immutable Form. The gearkeeper is immune to any spell or effect that would alter its form.

Rapid Shifting. Opportunity attacks made against the gearkeeper have disadvantage.

Whirling Blades. Any creature that starts its turn within 5 feet of the gearkeeper takes 4 (1d8) slashing damage.

Actions

Multiattack. The gearkeeper makes two Arm Blade attacks, or one Arm Blade attack and one Spear Launcher attack.

Arm Blade. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit:18 (3d8 + 5) slashing damage.

Spear Launcher. Ranged Weapon Attack: +9 to hit, range 90 ft., one target. Hit:12 (2d6 + 5) piercing damage, and the target is knocked prone.

Shrapnel Blast (Recharge). The gearkeeper jettisons a spray of jagged metal in a 30-foot cone. Each creature in the area must make a DC 15 Dexterity saving throw, taking 21 (6d6) piercing damage on a failed save, or half as much damage on a successful one.

Lore

Rolling, deadly whirlwinds of metal plates and curving blades, these clockwork automatons were initially designed by tinkerers and mage engineers to be sentries and guardians in the deepest of vaults during the Age of Arcanum. While most of these majestic and deadly curiosities have fallen to rust and ruin, forgotten along with their long-destroyed and buried societies, some continue to patrol the tunnels and pathways of forgotten tombs and dungeons, following their original operations and…