Ashen Seraphina of the Pyrothon

Devoted Princess. Ashen always knows the location of any creature that she has turned into ash figures inside her dungeon as long as they are on the same plane of existence.  If an ash figure takes any damage Ashen knows immediately how they were damaged and who has damaged them.

 Spellcasting. Ashen is a 5th-level spellcaster. Its spellcasting ability is [Intelligence] (spell save DC 17, +9 to hit with spell attacks). Ashen has following spells prepared:
At will: [detect magic], [fog cloud], [shield] 
3 slots: [blindness/deafness], [hold person], [suggestion]
2 slots: [bestow curse], [counterspell], [fear]
1 slot: [greater invisibility], [dominate person]

Marble-Skinned. Ashen's skin is made of a dense obsidian like material, making her natural armor extremely tough and resilient.  Whenever she takes any damage from a source other than psychic, the damage dealt is reduced by 5

Immutable Form. Ashen is immune to any spell or effect that would alter her form.

Pyrothon Vitality: pyrothons have a deep connection with fire, so much so that it rejuvenates Ashen. Whenever Ashen is hit with a fire-based attack, whether it's a spell or a weapon imbued with fire, she absorbs some of the fire energy to heal herself.
    When Ashen is subjected to [fire] damage, she can use her reaction to gain hit points equal to half the fire damage dealt, rounded down (minimum of 1). This represents Ashen absorbing the fire to heal her wounds.
    If the [fire] damage is from a spell, Ashen gains additional hit points equal to the spell's level.

Ashen's Pyroclastic Gaze.  When a creature that can see Ashen's eyes start it's turn withing 30 feet of her, Ashen can force that one creature to make a DC 16 Constitution saving throw as long as she isn't incapacitated and can see the creature. 
*Attack Description*: Ashen's eyes glow with an intense flame. The target must succeed on a DC 16 Constitution saving throw or begin to feel an intense burning sensation.

**Critical Failure (Roll of 1)**: If the target rolls a 1, they are immediately turned into a pile of ash, effectively removing them from the battle.
**Failure by 6 or more (Roll of 10 or less)**: If the target's saving throw fails by 6 or more, they start to burn from the inside. They take (2d10) [fire] damage at the start of their next turn. If they fail the saving throw on their next turn, they are turned into a pile of ash.
**Failure (Roll of 11-15)**: If the target fails the saving throw but not by 6 or more, they take (2d10) [fire] damage. They can repeat the saving throw at the end of their next turn, ending the effect on a success.
**Success (Roll of 16 or more)**: If the target succeeds on the saving throw, they resist the effects of Ashen's gaze for the remainder of the encounter.

 Embers of Kossuth When Ashen enters her lair if she's below half her health she will reset her health to 140 and she recharges her Ashen's Pyrothon Breath.  Additionally, she can use the options listed in her Legendary Actions for 1 hour, provided she remains in her lair.  This ability immediately ends if Ashen leave her lair or is killed.

Multi Attack. Ashen makes two melee attacks: One with Flaming Needle and one with her Snake hair
Flaming Needle. Melee Weapon Attack: +11 to hit, reach 5 ft., 1 target. Hit: 10 (1d8 + 6) magical [piercing] damage plus an additional (1d6) [fire] damage.
Snake Hair. Melee Weapon Attack: +8 to hit, reach 5 ft., 1 target. Hit: 10 (2d6 + 3) [piercing] damage plus an additional 10 (3d6) [poison] damage.

Arcane Bolt. RangedWeapon Attack: +9 to hit, range 240 ft., 1 target. Hit: 19 (3d10 + 3) [force] damage.

Ashen's Pyrothon Breath (5-6 Recharges)
All creatures within a 30-foot cone originating from Ashen.

*Attack Description*: Ashen exhales a cloud of poisonous, flammable gas. All creatures within the area must make a DC 16 Constitution saving throw or be poisoned.

**Poisoned State (Round 1)**: On a failed save, a creature is poisoned until the end of its next turn. While poisoned in this way, the creature takes 2d8 poison damage at the start of its turn.
**Ignition (Round 2 and onwards)**: If any fire damage is dealt within the area of the gas cloud (from any source), the cloud ignites. All creatures within the area must make another DC 16 Constitution saving throw.
**Critical Failure (Roll of 1)** If the creature rolls a 1, they are immediately turned into a pile of ash, effectively removing them from the battle.
**Failure**: On a failed save, a creature takes fire damage equal to the poison damage it took on the previous round and is no longer poisoned.
**Success**: On a successful save, a creature takes half as much fire damage and is no longer poisoned.
    When the gas has been ignited there is no longer any poison and it's a flash fire.

Animate Statue. (Recharge 4-6).  Ashen can choose up to five ash statues that she can see to animate at her will.  The targets use the petrified minion stat block and take their durn directly after Ashen following Ashen's command.  The maximum statues that can be animated is 10 at a single time.  
Ashen must concentrate on this ability and if her concentrations breaks (similar to a spell) the statutes will fall into a pile of ash. 

 Ashen can take 3 legendary actions choosing from the options below.  Only one legendary action can be used at a time and only at the end of another creatures turn.  Ashen regains spent legendary actions at the start of her turn.

Sudden Strike. Ashen make an attack with her Snake Hair, Flaming Needle, or Arcane Bolt.

Fighting Retreat. Ashen moves up to her speed without provoking opportunity attacks.

Shake it off (costs 2 Actions). Ashen makes a saving throw to end one condition or magical effect afflicting her.

Embers of Kossuth. If Ashen has used her Embers of Kossuth ability she can use the additional legendary action options listed below.  
Kossuth's prison.  Ashen chooses 1 creature she can see within 60 feet of her and attempts to encase them in a magical cube of golden/red fire energy.  The target must succeed on a DC 16 Charisma saving throw or be imprisoned in a magical transparent box.  The box measures 10'x10'x10', has an AC of 10, & 50 HP.  It's immune to all damage except force damage.  A creature inside the box can't leave it by any means (including teleportation to another plane of existence) but can otherwise move around and act freely inside the 10'x10'x10'. The creature can't be targeted for melee or spells while imprisoned however can be seen but not heard.  Ashen's Pyroclastic Gaze still functions as normal.  The imprisoned creature can attempt the saving throw again at the end of each of it's turns freeing itself on a DC 16 Charisma however if the saving throw fails the creature will now take 10 (3d6) psychic damage.

Inferno Trinity Strike (costs 2 actions). Ashen moves up to her speed toward a creature she can see and makes three melee weapon attacks against them.