Adult Copper Dragon

Legendary Resistance (3/Day, or 4/Day in Lair). If the dragon fails a saving throw, it can choose to succeed instead.

Acid Breath. Dexterity Saving Throw: DC 18, each creature in an 60-foot-long, 5-foot-wide Line. Failure: 54 (12d8) Acid damage. Success: Half damage.

Multiattack. The dragon makes three Rend attacks. It can replace one attack with a use of (A) Slowing Breath or (B) Spellcasting to cast Mind Spike (level 4 version).

Rend. Melee Attack Roll: +11, reach 10 ft. 17 (2d10 + 6) Slashing damage plus 4 (1d8) Acid damage.

Slowing Breath. Constitution Saving Throw: DC 18, each creature in a 60-foot Cone. Failure: The target can't take Reactions; its Speed is halved; and it can take either an action or a Bonus Action on its turn, not both. This effect lasts until the end of its next turn.

Spellcasting. The dragon casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 17): - **At Will:** Detect Magic, Mind Spike, Minor Illusion, Shapechange - **1/Day Each:** Greater Restoration, Major Image