Xasnil Dragon, Ancient

Deem Leem's bag o' Stuff

Traits

Xasnil Scales. The dragon regains 20 hit points at the start of its turn. If the dragon takes cold damage or has a level of exhaustion, this trait doesn't function at the start of the dragon's next turn. The dragon dies only if it is hit by an attack that deals 20 or more cold damage while the xasnil dragon has 0 hit points.
Sun’s warming rays. At the start of its turn, if the dragon has spent its previous 2 turns in direct sunlight, it can make a DC 26 Constitution check to remove 1 level of exhaustion.
Nature’s Wing and Claw. The dragon is immune to non-damaging negative effects of any storm. (ie. Hurricane winds)
Legendary Resistance (3/Day, or 4/Day in Lair). If the dragon fails a saving throw, it can choose to succeed instead.

Actions

Multiattack. The dragon makes three Rend attacks. It can replace one attack with a use of (A) Spellcasting to cast Dispel Magic (level 6 version) (B) Either of its breath weapons. 

Rend. Melee Attack Roll: +15, reach 10 ft. Hit: 16 2d8+7 Slashing damage plus 9 2d8 Fire damage. The target’s Hit Point maximum decreases by an amount equal to the fire damage taken.
Emerald Fire Breath (Recharge 5-6). Dexterity Saving Throw: DC 26, each creature in a 90-foot Cone. Failure: 71 13d10 Fire damage. Success: Half damage. The target’s Hit Point maximum decreases by an amount equal to the damage taken.
Solar Breath (2/Day). Constitution Saving Throw: DC 26, each creature in a 120-foot line. Failure: 97 15d12 Radiant damage and is blinded until the dragon’s next turn. Success: Half damage and isn’t blinded. Undead and oozes have disadvantage on this saving throw. Additionally, the dragon gains 3 level of exhaustion.
Spellcasting. The dragon innately casts one of the following spells, requiring no material components and using Wisdom as the spellcasting ability (spell save DC 21):

At will: Call Lightning, Cure Wounds, Detect Magic, Dispel Magic, Plant Growth, Scorching Ray, Spike growth, Shapechange (Beast or Humanoid form only, no Temporary Hit Points gained from the spell, and no Concentration or Temporary Hit Points required to maintain the spell)
3/day each: Banishment, Blink, Greater Restoration, Conjure Volley, Carion thorns
1/day each: Dimension Door, Wrath of Nature, Sun Burst

Legendary Actions

Legendary Action Uses: 3 (4 in Lair). Immediately after another creature’s turn, the dragon can expend a use to take one of the following actions. The dragon regains all expended uses at the start of each of its turns. 

Call Nature's aid. The dragon uses Spellcasting to cast either Plant Growth or Spike Growth.
Blazing Light. The dragon uses Spellcasting to cast Scorching Ray at 5th level.
Pounce. The dragon moves up to half its Speed, and it makes one Rend attack.