Adult Spirit Dragon

If the dragon fails a saving throw, it can choose to succeed instead.

The dragon makes three Rend attacks. It can replace one attack with a use of (A) Time-Warping Breath or (B) Spellcasting to cast Thunderwave.

Melee Attack +11, reach 10 ft. 15 (🎲2d8 + 6) 🗡️ Slashing damage plus 7 (🎲2d6) 💀 Necrotic damage.

CON Save DC 18, each creature in a 60-foot Cone [Area Of Effect].
Failure: 63 (🎲14d8) 💀 Necrotic damage.
Success: Half damage.

WIS Save DC 18, each creature that isn't currently affected by this breath in a 60-foot Cone [Area Of Effect].
Failure: The target's Speed is halved, it can't take Reactions, and it can take either an action or a Bonus Action on its turn, not both. It repeats the save at the end of each of its turns, ending the effect on itself on a success. After 1 minute, it succeeds automatically.

The dragon moves up to half its Speed, and it makes one Rend attack.

The dragon uses Spellcasting to cast Thunderwave.

The dragon magically raises broken, ancient ruins in a 20-foot-radius, 60-foot-high Cylinder [Area Of Effect] centered on a point it can see within 120 feet. Ground in the Cylinder [Area Of Effect] becomes Difficult Terrain. Each creature in the Cylinder [Area Of Effect] when it appears is subjected to the following effect. STR Save DC 18.
Failure: 5 (🎲2d4) 🔨 Bludgeoning damage, and the target has the Prone condition.
Success or Failure: The dragon can't take this action again until the start of its next turn.