```statblock
name: Mightingale
size: Medium
type: fey
subtype: sidhe
alignment: neutral
ac: 18
hp: 71
hit_dice: 13d8 + 13
speed: 30 ft.
stats: [11, 18, 13, 18, 16, 19]
saves:
- Intelligence: 5
- Wisdom: 6
- Charity: 7
skillsaves:
- History: 5
- Perception: 6
- Performance: 10
damage_immunities: fire, lightning
condition_immunities: charmed, frightened, petrified
senses: darkvision 120 ft., passive Perception 16
languages: Arak
cr: 7
spells:
- The mightingale's innate spellcasting ability is Charisma (spell save DC 15, +7 to hit with spell attacks). It can innately cast the following spells, requiring no material components.
- At will: detect thoughts, enthrall, legend lore, tongues (self only), suggestion, true strike
traits:
- [Magic Resistance, The mightingale has advantage on saving throws against spells and other magical effects.]
- [Sidhe Shape: Nightingale, As a bonus action, the mightingale magically polymorphs into a nightingale, or back into its humanoid form. Any equipment it is wearing or carrying is absorbed by the new form. In nightingale form, the mightingale gains the statistics of a raven, but retains its hit points, alignment, Intelligence, Wisdom, Charisma, and damage resistances and immunities.]
- [Sidhe Weapon: Mandolin, As a free action on its turn, the mightingale can create a mandolin in an unoccupied hand. While playing the mandolin, any creature within 120 feet of the mightingale that can hear it has disadvantage on saving throws against spells cast by the mightingale, but the mightingale cannot make weapon attacks while playing on its mandolin. The mightingale can only have one such instrument at any given time, and can dismiss it as a free action. The instrument is destroyed by exposure to sunlight.]
- [Sunlight Hypersensitivity, The mightingale takes 5 radiant damage when it starts its turn in bright sunlight. While in sunlight, it has disadvantage on attack rolls and ability checks.]
- [Unearthly Grace, The mightingale adds its Charisma modifier to its AC.]
actions:
- [Multiattack, The mightingale makes two rapier attacks.]
- [Rapier, Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. Hit: 7 (1d6 + 4) piercing damage]
```