Clockwork Angel

Unusual Nature. The angel doesn’t require air, food, drink, or sleep.

Clockwork Heart. While in their sculpture form, the angel looks like a regular statue. However, if creatures listen very carefully (by performing a DC 20 Investigation or Perception check) they can hear ticking coming from inside the angel, possibly preventing a nasty surprise, as per the DM's personal rulings..

Heating up!  Because the angel is steam-powered, getting hit with fire damage doesn't hurt the angel, instead it is forced to make a Flamethrower Attack on its next turn. Powered up, the attack does 5d6 instead of 5d4 damage.

Smoking. Due to its steam-powered nature, fighting or engaging with the angel in a closed-off or tight space will fill that room with smoke over time. As per the DM's personal ruling, the angel's opponents will start to experience some form of disadvantages or damage from the smoke.

Living Soul. As stated in the angel's description, the machinery makes use of alchemist fluids but still requires a living creature's brain and heart, which is why the angel can still be damaged by Psychic Attacks. Inside the angel, the "soul" can't remember it's original form however. While the angel can be charmed or frightened on a more instinctual level, the only way for the angel to remember who they once were is if the players try to tell the angel directly and must succeed on a DC 20 Persuasion check if they know the angel's original identity, or a DC 25 Persuasion check if they don't. Succeeding will make the angel exit combat, but the soul's reaction to the new body will probably be different depending from personality to personality.

Clockwork. Any character fighting the angel can see that the complex arrangement of its workings gives it a unique vulnerability. Any character within 5 feet of the construct can use an action to attempt a DC 14 Dexterity check using jeweler's tools or thieves' tools or a Sleight of Hand check using an item that the DM thinks they could realistically jam into its mechanism. On a success, the angel takes 15 bludgeoning damage as it components start to grind. If unsuccessful, the angel can use a Reaction to make a Blade Attack against the attacker.

Multiattack. The angel makes three Blade Attacks, or it makes a Flamethrower followed by a Molten Coal attack. For the three Blade Attacks, the angel does these on different targets, if possible. Envision this multiattack like a spinning dance of blade.

Blade Attack. The angel uses their blade stilts to perform a Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: 10 (1d12 + 2) slashing damage.

Flamethrower. Ranged Techinical Attack: The angel opens its furnace hatch to let out a 30-foot cone of fire. Each creature in the area must make a DC 15 Dexterity saving throw, taking 5d4 fire damage on a failed save, or half as much damage on a successful one.

Deslagging. Melee Techinical Attack: The angel gets rid of some excess coal and slag, opening its back hatch and dumping burning coal onto a 5 by 10 ft. square within melee range. If creatures are on the targeted squares, they must make a DC 10 Dexterity saving throw or take 1d8 fire damage. Afterwards, the burning coals are active for one minute or until another creature takes an action (as per the DM's regard) to remove or put out the coals. If a creature end their turn on the hot coals, they will take 1d8 fire damage. The coals, while burning, constitute difficult terrain.

Quick Retreat. Using its blade-stilts, the angel can jump as a bonus action. Players in melee range must succeed on a DC 15 Dexterity saving throw to react fast enough to engage in an opportunity attack.

Protective Wings (Recharge 5–6). As a reaction, the angel can wrap its mechanical wings around itself, granting it +5 AC until its next turn. Recharges are rolled on the angel's turn if the reaction was used. If the angel takes 30 points of damage while the wings are protecting it (in one round, so before it's the angel's turn again), the wings permanently break off.