A bit of catchy, repetitive music emanates from nowhere, drifting and moving as if dancing in the empty air.
Medium aberration, chaotic neutral
Armor Class 15
Hit Points 39 (6d8 + 12)
Speed fly 50 ft. (hover)
|1 (-5)||20 (+5)||15 (+2)||5 (-3)||12 (+1)||17 (+3)|
Skills Perception +3
Damage Vulnerabilities thunder
Damage Resistances acid, cold, fire, lightning; bludgeoning, piercing, and slashing from nonmagical weapons
Damage Immunities poison
Condition Immunities charmed, exhaustion, grappled, paralyzed, petrified, poisoned, prone, restrained, unconscious
Senses darkvision 60 ft., passive Perception 13
Languages telepathy 200 ft.
Challenge 4 (1,100 XP)
- Incorporeal Movement. The ostinato can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.
- Invisibility. The ostinato is invisible as per a greater invisibility spell.
- Magic Resistance. The ostinato has advantage on saving throws against spells and other magical effects.
- Multiattack. The ostinato makes two cacophony ray attacks.
- Cacophony Ray. Ranged Spell Attack: +7 to hit, range 60 ft., one target. Hit: 10 (3d6) thunder damage.
- Aural Symbiosis (1/Day). One humanoid that the ostinato can see within 5 feet of it must succeed on a DC 13 Charisma saving throw or the ostinato merges with it, becoming an enjoyable, repetitive tune in its host’s mind. The ostinato can’t be targeted by any attack, spell, or other effect. The target retains control of its body and is aware of the ostinato’s presence only as a melody, not as a living entity. The target no longer needs to eat or drink, gains the ostinato’s Magic Resistance trait, and has advantage on Charisma checks. It also has disadvantage on Wisdom saving throws and it can’t maintain concentration on spells or other effects for more than a single turn. The target can make a DC 13 Wisdom (Insight) check once every 24 hours; on a success, it realizes that the music it hears comes from an external entity. The Aural Symbiosis lasts until the target drops to 0 hit points, the ostinato ends it as a bonus action, or the ostinato is forced out by a dispel evil and good spell or comparable magic. When the Aural Symbiosis ends, the ostinato bursts forth in a thunderous explosion of sound and reappears in an unoccupied space within 5 feet of the target. All creatures within 60 feet, including the original target, take 21 (6d6) thunder damage, or half damage with a successful DC 13 Constitution saving throw. The target becomes immune to this ostinato’s Aural Symbiosis for 24 hours if it succeeds on the saving throw or after the Aural Symbiosis ends.
- Voracious Aura (1/Day). While merged with a humanoid (see Aural Symbiosis), the ostinato feeds on nearby creatures. Up to nine creatures of the ostinato’s choice within 60 feet of it can be targeted. Each target must succeed on a DC 13 Charisma saving throw or take 3 (1d6) necrotic damage and have its hit point maximum reduced by the same amount. Victims notice this damage immediately, but not its source.
Born from Drama. Incredibly moving arias, passionate performances, and ditties that drive you mad are often the product of ostinatos. These creatures of living music are born from overwrought emotions, and they feed off the vitality and personality of mortals.
Song Searchers. Ostinatos wander the mortal world as repetitive snippets of song, searching for hosts and rich feeding grounds. They enter hosts secretly, remaining undetected to prolong their voracious feasting as long as possible.
Tome of Beasts. Copyright 2016, Open Design; Authors Chris Harris, Dan Dillon, Rodrigo Garcia Carmona, and Wolfgang Baur.