Experiment 3: The Winged Haunter
Components: harpy bile, nymph blood, purple worm digestive juice, dire wolf urine, howler spinal fluid.

Method: Having been provided with a diverse array of carafes, decanters and beakers filled with reeking juices, I was immediately minded to combine them into some kind of ooze or jelly. In particular, I was keen to make use of the highly potent purple worm acid to create a stronger variety of ooze.

Unfortunately, I left the mixture unattended overnight and Rasan, one of my apprentices, mistook it for an experimental potion. At least, that is what I have inferred from the subsequent developments.

Results: I believe that Rasan died within moments of ingesting the mixture - the purple worm acid will surely have eaten away his innards and inflicted various other grisly tortures. The creature continues to live, however. Therefore, I conclude that it is an undead, animated either by the enchantments I placed on the mixture, or by some spell cast by Rasan before he died.

Now this monster prowls the rooftops by night - for it has sprouted feathered wings and developed a hunger for flesh (unless there was more to Rasan than I realised). Its vocalisations are most distinctive, being a sort of cross between a piercing howl and a seductive siren-song. Those who hear it are subjected to a powerful psychic effect that leaves them stunned and confused for several minutes.

The townsfolk have taken to calling it the Winged Haunter, presumably because of its eerie song. Those who have sighted it claim that it is covered in dark brown fur, and that it prefers to hunt human babies.

I remain hopeful that this episode will end well, however. The Haunter's legend has already begun to spread and should draw all manner of adventuresome folk to the region, who will surely be able to supply me with more monster components for my experiments!

Spoiler: Stats
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Winged Haunter
Medium undead, chaotic evil

Armour Class 12
Hit Points 45 (7d8 + 14)
Speed 30 ft., fly 40 ft.

STR DEX CON INT WIS CHA
15 (+2) 15 (+2) 14 (+2) 10 (+0) 11 (+0) 12 (+1)

Skills Perception +2, Stealth +4
Damage Resistances Acid, Necrotic, Poison
Senses darkvision 60ft., passive Perception 12
Languages Common, Infernal
Challenge 2 (450 XP)


Innate Spellcasting. The winged haunter's innate spellcasting ability is Charisma (spell save DC 11; +3 to hit). The winged haunter can innately cast the following spells, requiring no material components:

At will: Chill Touch, Mage Hand, Prestidigitation, Ray of Frost
1/day: False Life, Fog Cloud, Magic Missile

Actions

Multiattack. The winged haunter makes two attacks with its claws.

Claws. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 7 (2d4 + 2) slashing damage.

Haunting Song. The winged haunter sings a magical melody. Every humanoid within 100 feet of the haunter that can hear the song must succeed on a DC 11 Wisdom saving throw or be incapacitated and have its movement speed halved until the song ends. The haunter must take a bonus action on its subsequent turns to continue singing, though it can stop singing at any time. The song ends if the winged haunter is incapacitated.
A creature subjected to this effect may repeat the saving throw at the end of each of its turns. If the saving throw is successful, the effect ends on it. A target that successfully saves is immune to the haunter's song for the next 24 hours.