Ancient Silver Dragon

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

The monster makes three attacks. It can replace one attack with a use of (A) or (B) Spellcasting to cast (level 2 version).

Constitution Saving Throw: DC , each in a -foot Cone.
Failure: damage.
Success: Half damage.

. .

Constitution Saving Throw: DC , each in a -foot Cone.
First Failure: The target has the Incapacitated condition until the end of its next turn, when it repeats the save.
Second Failure: The target has the Paralyzed condition, and 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 monster casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC , +15 to hit with spell attacks):
At Will: Detect Magic, Hold Monster, Ice Knife (level 2 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)
1/Day Each: Control Weather, Ice Storm (level 7 version), Teleport, Zone of Truth