Athasian Dragon, Dragon of Tyr

Innate Spellcasting (Psionics). The Dragon is a 20th level manifester. The Dragon of Tyr’s spellcasting ability is Charisma (spell save DC 24, +16 to hit with spell attack). The dragon can innately cast the following spells, requiring no material components:

• At will: Bigby’s hand (the hand is invisible), clairvoyance, gaseous form, gust of wind, shield, telekinesis, vampiric touch
• 3/day: power word stun, scrying
• 1/day: antilife shell, foresight, forcecage, time stop

Spellcasting. The dragon is a 20th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 24, +16 to hit with spell attacks). It has the following sorcerer spells prepared:

• Cantrips (at will): acid splash, blade ward, firebolt, minor illusion, prestidigitation, true strike
• 1st Level (4 slots): charm person, sleep
• 2nd Level (3 slots): hold person, ray of enfeeblement
• 3rd Level (3 slots): fear, hypnotic pattern
• 4th Level (3 slots): confusion, dimension door
• 5th Level (3 slots): hold monster, wall of stone
• 6th Level (2 slots): mass suggestion
• 7th Level (2 slots): finger of death, teleport
• 8th Level (1 slot): dominate monster
• 9th Level (1 slot): power word kill

Defiler. The Dragon of Tyr is a 28th level Dragon. Like other arcane casters on Athas, it can empower its spells with the life energy of vegetation in her immediate environment.

When it casts an arcane spell of 1st level or higher using a spell slot, it can spend a number of defiliing points limited by the vegetation of the environment or its proficiency bonus (+8), whichever is lower.

Plant creatures and objects within a 10 ft radius of the defiler take 1d6 necrotic damage per defiling point spent. A creature or magical object can make a CON save for half damage. Plants reduced to 0 hp wither and decompose instantly into infertile ash. The radius changes to 20 feet for spells 6th level and above. Most objects have few hit points and rely upon a hardness threshold to survive, which the defiling effect ignores.

The Dragon's cantrips and psionic powers do not cause defilement. It cannot cast arcane spells when standing in completely defiled spaces (but see Tree of Life bellow).

As a defiler, the Dragon has an aura that is visible under certain circumstances. The Dragon is subject to spells, powers, and other traits that affects defilers, such as Detect Defiler or a Preserver's Backlash ability.

Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Limited Magic Immunity. The dragon can’t be affected or detected by spells of 5th level or lower unless it wishes to be. It has advantage on saving throws against all other spells and magical effects.

Mental Defenses. The dragon is immune to any effect that would sense its emotions or read its thoughts, including divination spells. Even wish spells and spells or effects of similar power cannot affect the dragon’s mind or gain information about it.

Multiattack. The dragon makes three attacks: one with its bite and two with its claws. The dragon can also cast or manifest a spell. The dragon can cast and manifest two spells but loses one claw attack.

Bite. Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 19 (2d10 + 8) piercing damage.

Claws. Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit: 22 (4d6 + 8) slashing damage.

Tail. Melee Weapon Attack: +16 to hit, reach 20 ft., one target. Hit: 17 (2d8 + 8) bludgeoning damage.

Scorching Sand Breath (Recharge 6). The dragon exhales scorching hot sand in a 90-foot cone. Each creature in that area must make a DC 24 Dexterity saving throw, taking 78 (12d12) fire damage plus 78 (12d12) bludgeoning damage on a failed saving throw, or half as much damage on a successful one.

Raze. The Dragon can burn a spell slot just to defile. The radius of the defilement is 10 feet for a 1st thru 3rd level spell, 20 feet for a 4th-6th level spell, and 30 feet for a 7th-9th level spell. The dragon affects plant and animal targets with its defiliement, which take 1d6 damage per defiling point that could be generated, plus 1d6 damage per spell level. The dragon is immune to its own raze.

War Caster. The Dragon can cast a spell with a range of touch and a casting time of 1 action in lieu of an opportunity attack. 

Spear Mastery. The Dragon can make an opportunity attack against any creature as it enters or moves within the reach of its claws. 

Shield. The Dragon can grant itself a +5 bonus to AC when subject to an attack that would hit it. The bonus persists until the start of the dragon's next turn. 

Counterspell. As a reaction to witnessing a spell being cast, the dragon can cast counterspell.

The dragon can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The dragon regains spent legendary actions at the start of its turn.

At-Will Spell. The dragon casts one of its at-will spells.

Detect. The dragon makes a Wisdom (Perception) check.

Psionic Attack. The dragon uses one of its at-will psionic powers.

Tail Attack. The dragon makes a tail attack.

Dramatic Resurgence (Mythic Trait; recharges after a long rest).  If the Dragon of Tyr is reduced to 0 hit points, it does not die or fall unconscious. Instead, she regains 499 hit points and uses its Psionic Pulse ability for no cost. In addition, the Dragon immediately rises to an altitude of 10 ft and gains Fly 60 ft (Hover) and immunity to the prone condition, both for 1 for 1 minute. For that minute, the Dragon includes a tail attack in its multiattack and can use the following additional legendary actions.

Claw. The Dragon makes a claw melee attack.

Bite. The Dragon makes a Bite attack, targeting one creature. 

Accelerated Spell. The Dragon can use a legendary action to cast a spell or manifest a power with a casting time of one bonus action. It can use defiling to make an arcane spell with a casting time of 1 action into a bonus action spell to use this way.