Children of the Raven Queen

The Archon referred to as the Raven Queen by Isabel, used material agents of hers to conduct missions across both the Undercity and Santa Corazón. It is unknown how these creatures came to be; however, in Luis' dream about Sinola in Under Auspicion, Sinola hypothesizes that at least the Mockinghounds might be genetically modified creatures.

Description
Standing slightly larger than a wolf, the Mockinghound's canine form is covered in black, leopard-spotted, pelts showing the slender skeleton beneath. It's almost reptilian head is covered in a bony growth mimicking the skull of a diapsid above the mandible and the jaw is filled with tons of sharp, predatory teeth. A long feline tail trails behind it's legs, that end in goat-like hooves. Covering the shoulders, spine, ankles, and tail, are mangy, black, crows' feathers with quill-like structures protruding from the mangy mass. Piercing from the inky black of it's form, two gleaming, white dots pear into it's prey from the shadows.

Abilities

 * Mimic. The mockinghound can mimic any sounds it has heard, including voices. A creature that hears the sounds can tell they are imitations with a successful Wisdom (Insight) check.
 * Nimble Escape. The mockinghound can take the Disengage or Hide action as a bonus action on each of its turns.
 * Surprise Attack. If the mockinghound surprises a creature and hits it with an attack during the first round of combat, the target takes extra 6 damage from the attack.
 * Sure-Footed. The mockinghound has advantage on Strength and Dexterity saving throws made against effects that would knock it prone.

Actions

 * Multiattack. The mockinghound makes two bite attacks.
 * Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) piercing damage.
 * Read Thoughts. The mockinghound magically reads the surface thoughts of one creature within 60 feet of it. The effect can penetrate barriers, but 3 feet of wood or dirt, 2 feet of stone, 2 inches of metal, or a thin sheet of lead blocks it. While the target is in range, the mockinghound can continue reading its thoughts, as long as the mockinghound concentration isn't broken (as if concentrating on a spell). While reading the target's mind, the crocotta has advantage on Wisdom (Insight) and Charisma (Deception, Intimidation, and Persuasion) checks against the target.

Origin and Uses
Sinola believes that these were once Crocottas, hyena-like creatures from the continent of Kyphon. Considering the origin of Sandalphons, it is likely that they were once Crocottas that were killed and possessed by Echoes.

The Mockinghounds were used for specifically targeted attacks, like the assault on the Rookery, as well as, supporting infantry movements by undermining enemy defenses, as seen at the Battle of the Crystal Chapel.

Appearances

 * Chapter V: A Bold Bluff
 * Chapter VI: Friendly Fire
 * Chapter XII: What a Way to Die
 * Chapter XIV: I Only Have Eyes for You
 * Chapter XV: The Weight of Your Sins

Description
Echoes in their base form appear as an oddly textured black ooze, that appears to roll and writhe in reaction to organic matter. However, Echoes most notable feature appears to be their ability to shapeshift into a multitude of forms; including black hats, stones, and most notably ravens. In these forms, they passed as typical objects before striking in their more amoeba-like form.

Abilities

 * Mimic. The raven can mimic simple sounds it has heard, such as a person whispering, a baby crying, or an animal chittering. A creature that hears the sounds can tell they are imitations with a successful DC 10 Wisdom (Insight) check.
 * Shapechanger. The mimic can use its action to polymorph into an object or back into its true, amorphous form. Its statistics are the same in each form. Any equipment it is wearing or carrying isn 't transformed. It reverts to its true form if it dies.
 * Adhesive Touch (Ooze Form only) The mimic adheres to anything that touches it. A Huge or smaller creature adhered to the mimic is also grappled by it (escape DC 13). Ability checks made to escape this grapple have disadvantage.
 * False-Appearance (Object/Animal Form only). While the mimic remains motionless, it is indistinguishable from an ordinary object or bird.
 * Grappler. The mimic has advantage on attack rolls against any creature grappled by it.

Actions

 * Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) piercing damage.
 * Pseudopod.  Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: (1d8 + 3) bludgeoning damage. If the mimic is in object form, the target is subjected to its Adhesive trait
 * Body Thief. The echo targets a creature within 5 feet of it that is incapacitated, or that has died within the last minute. An incapacitated creature must succeed on a DC 12 Intelligence saving throw or take 54 (12d8) psychic damage. If this damage reduces the target to 0 hit points, the target heals up to 1 of their hit dice and is possessed by the echo. If the target was dead, it returns to life with 1 of their hit dice and is possessed by the echo. The echo consumes the brain of a creature it possesses, and replaces it. The echo can’t be targeted by any attack, spell, or other effect, except protection from good and evil, and it retains its alignment, Intelligence, Wisdom, and Charisma. It otherwise uses the possessed target’s statistics, gaining access to the target’s knowledge, class features, and proficiencies. The possession lasts until the body drops to 0 hit points, the echo ends it as a bonus action, or the echor is forced out by an effect like protection from good and evil. When the possession ends, the echo reappears in an unoccupied space within 5 feet of the body. The body then dies, unless its brain is restored within 1 round.

Origin and Uses
It is unclear as to how the Echoes were created, as they appear to be nothing more than extremely talented and malicious goo-balls. It's likely that they were created by the Raven Queen directly, or derived from a Cawcophony.

The Echoes are extremely versatile with their abilities to transform into a variety of creatures and possess the bodies of the deceased and incapacitated. They appeared to also have a direct line to the Raven Queen, allowing them to survey the city from the sky. In I Only Have Eyes for You, it was revealed that the Echoes could inhabit corpses and control them, creating easy disposable infantry for the later battle.

Appearance

 * Chapter VII: Under Auspicion
 * Chapter VIII: Isabel
 * Chapter IX: Under Hallowed Ground (background)
 * Chapter XI: Zoodled (background/possessed bar-crawlers)
 * Chapter XII: What a Way to Die
 * Chapter XIII: For the Last Time (background)
 * Chapter XIV: I Only Have Eyes for You
 * Chapter XV: The Weight of Your Sins
 * Chapter XVI: A House of Dreams (background/Luis' dreams)
 * Chapter XVI: Sentimentalism (background)

Description
Appearing as an angel of jet and carbon, the Sandalphon has long and gangly limbs along with a desiccated torso. It's limbs end in jagged and sharp points, talons on the hands, and two singular points on the feat. Black ooze, shards of glass, and strings of wire spread along the rotted skin of the creature, like an armor. Two wide, raven feather wings dwarf the corpse body of Sandalphon, and is wreathed in barbed wire and jutted with glass. Adorning the head of this creature is a gramophone, with tubes extending down it's mouth and across it's body. Within this macabre music player, is a skull, the last vestige of the human that this creature once was.

Abilities

 * Mimic. The sandalphon can mimic any sounds it has heard, including voices. A creature that hears the sounds can tell they are imitations with a successful DC 17 Wisdom (Insight) check.
 * Blind Senses. The sandalphon can't use its blindsight while deafened and unable to smell.
 * Keen Hearing. The sandalphon has advantage on Wisdom (Perception) checks that rely on hearing or smell.
 * Gargoyle Camouflage. The sandalphon has advantage on Dexterity (Stealth) checks made to hide in derelict terrain

Actions

 * Multiattack. The sandalphon makes three attacks: two with its claws and one with its Static Discharge or Vocal Blast.
 * Claws. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 8 (2d4 + 3) slashing damage.
 * Static Discharge. Ranged Weapon Attack: +3 to hit, range 10 ft., one creature. Hit: 5 (2d4) thunder damage.
 * Vocal Blast (Recharge 5-6). The sandalphon emits a violent shockwave in a 30-foot cone. Each creature in that area must make a DC 14 Constitution saving throw. On a failed save, the creature takes 21 (6d6) thunder damage and is deafened for 1 minute. An affected creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. On a successful save, the creature takes half as much damage and isn't deafened.

Origin and Uses
From what we can tell from the Sandalphon that strongly resembled Detective Pérez, which was crucified by the Sword's sealing ritual, Sandalphons appear to have once been deceased creatures possessed by an Echo that have either been selected by the Raven Queen or possibly possessed for long enough to gestate into the fully fleshed out Sandalphon form.

Sandalphons are used by the Raven Queen as her highest lieutenants, they can harness her ability to override creature's will, and have their own audio and martial abilities. They are seen managing her assets, including the nest discovered in What a Way to Die, and spearheading her armies, as seen in The Weight of Your Sins.

Appearance

 * Chapter XI: Zoodled (obscured)
 * Chapter XII: What a Way to Die
 * Chapter XIV: I Only Have Eyes for You
 * Chapter XV: The Weight of Your Sins
 * Chapter XVI: Sentimentalism (background)