Ancient Brass Dragon

4/day (5/day in lair). If the ancient brass dragon fails a saving throw, it can choose to succeed instead.

The ancient brass dragon makes three Rend attacks. It can replace one attack with a use of (A) Sleep Breath or (B) Spellcasting to cast Scorching Ray (level 3 version).

Melee Weapon Attack: +14 to hit, reach 15 ft.. Hit: 19 (2d10 + 8) slashing plus 7 (2d6) fire damage.

Recharge 5–6. Dexterity Saving Throw: DC 21, each creature in a 90-foot-long, 5-foot-wide Line.
Failure: 58 (13d8) fire damage.
Success: Half damage.

Constitution Saving Throw: DC 21, each creature in a 90-foot Cone.
Failure: The target has the Incapacitated condition until the end of its next turn, at which point it repeats the save.
Second Failure: The target has the Unconscious condition for 1 minute. This effect ends for the target if it takes damage or a creature within 5 feet of it takes an action to wake it.

1 use per day. The ancient brass dragon casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 20):
At Will: Detect Magic, Minor Illusion, Scorching Ray (level 3 version), 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), Speak with Animals
1/Day Each: Control Weather, Detect Thoughts

The ancient brass dragon uses Spellcasting to cast Scorching Ray (level 3 version).

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

Dexterity Saving Throw: DC 20, 1 creature the ancient brass dragon can see within 120 feet.
Failure: 36 (8d8) fire damage, and the target's Speed is halved until the end of its next turn.
Failure or Success: The ancient brass dragon can't take this action again until the start of its next turn.