ancient wyrvern fiend

legendary resistance (3/day): If it failed a save, it can choose to succeed instead.

Magic resistance: Advantage against spell saves. 

Magic attacks: All melee attacks count as magical.

devils sight: Can see through magical darkness as if it was normal.

Frightening presence: Every creature within 120ft of direct sight of the fiend must succeed a DC 24 wisdom save or become frightened for one minute. They may repeat the save at the end of their next turn and once they succeed they are immune to this effect for 24h.

True flame: All fire damage the Wyrvern deals goes through magical resistance and treats immunity as resistance to fire damage, its magic is one that burns all, even beings of pure flame.

Spellcasting. The Wyrvern's spellcasting ability is [charisma] (spell save DC 24). The Wyrvern has following spells prepared:
(at will): Detect magic, Wall of fire, dominate person.
(3 slots): Wall of fire, circle of death, power word stun

Multiattack. Makes an action of frightening presence, then 4 attacks. 2 with its claw, 1 with its bite, and 1 with its tail.

claw. Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: 18 (2d8 + 10) slashing damage plus 9 (3d6) fire damage.

Bite. Melee Weapon Attack: +18 to hit, range 15ft, one target. Hit: 20 (2d10 + 10) Piercing damage plus 18 (6d6) fire damage and target can be grappled by choice.

tail. Melee Weapon Attack: +18 to hit, range 20ft, one target. Hit: 22 (3d8+ 10) Bludgeoning  damage plus 4 (1d8) piercing damage. Target must make a DC 24 constitution save or take 4d6 damage from a searing wound of flame. The target takes the damage at the start of their next turn, and takes an additional 4d6 damage if they fail the save from another hit. The effect ends once they succeed a DC 18 medicine check or heal themselves.

Soul absorbing breath (reacharge 5-6). every target within a 120ft cone must succeed a dc 24 dex save or take 20d6 fire damage, halved on a success. At the start of their turn and on each turn afterwords, if they failed the save, they take 10d6 additional fire damage from the flames melting their souls, and all damage taken by this effect heals the wyvern by that amount. The target can make a constitution save at the start of their turn (DC 24) and end this effect on a success.

___

molten scales. Can force a target to take 1d10 necrodic damage as a reaction once he is hit with an attack as flames of darkness burst from the wound. 

The Wyrvern gets 3 legendary actions per turn, which it can use at the end of players first action, whether it be used to attack, dash, or cast a spell. 

detect (1). The Wyrvern makes a perception check.

quick spell (1).  The Wyrvern cast an at will spell.

wing attack: The Wyrvern beats its wings, every creature within 30ft must succeed a DC 25 dexterity save or take 2d6+10 bludgeoning damage, halved on a success, and is knocked prone. The Wyrvern can move up to halve its speed with this action.

Mythic Action Name. Enter the description for how mythic actions work for your monster here.

Mythic Action Name (Costs # Actions). Enter the description for your mythic action.