DND Monsters: Duergar Hammerer
From: Icewind Dale: Rime of the Frostmaiden, Mordenkainen's Tome of Foes, Mordenkainen Presents: Monsters of the Multiverse
Medium Construct, Lawful Evil
Str 17 +3 Dex 7 -2 Con 12 +1 Int 5 -3 Wis 5 -3 Cha 5 -3
Immunities Poison Cannot Be Charmed, Exhausted, Frightened, Paralyzed, Petrified, Poisoned
Languages Understands Dwarvish but can't speak
Engine of Pain. Once per turn, a creature that attacks the hammerer can target the duergar trapped in it. The attacker has disadvantage on the attack roll. On a hit, the attack deals an extra 5 (1d10) damage to the hammerer, and the hammerer can respond by using its Multiattack with its reaction.
Siege Monster. The hammerer deals double damage to objects and structures.
Multiattack. The hammerer makes two attacks: one with its claw and one with its hammer.
Claw. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) bludgeoning damage.
Hammer. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) bludgeoning damage.
Monsters of the Multiverse
Only thing really that changed was Engine of Pain is now a Reaction and now functions as below
Engine of Pain. Immediately after a creature within 5 feet of the hammerer hits it with an attack roll, the hammerer makes a Hammer attack against that creature.