Ancient Silver Dragon

From Monster Manual, page 116.

**Hit Points:** 487 (25d20 + 225)
 **STR**
30 (+8)
10 (0)
29 (+9)
18 (+4)
15 (+2)
 **Saving Throws:** Dex +7, Con +16, Wis +9, Cha +13
**Skills:** Arcana +11, History +11, Perception +16, Stealth +7
**Damage Immunities:** cold
**Senses:** blindsight 60 ft., darkvision 120 ft., passive Perception 26
**Languages:** Common, Draconic
 ***Legendary Resistance (3/Day).*** If the dragon fails a saving throw, it can choose to succeed instead.
 ***Multiattack.*** The dragon can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.
***Bite.** Melee Weapon Attack:* +17 to hit, reach 15 ft., one target. *Hit:* 21 (2d10 + 10) piercing damage.
***Claw.** Melee Weapon Attack:* +17 to hit, reach 10 ft., one target. *Hit:* 17 (2d6 + 10) slashing damage.
***Tail.** Melee Weapon Attack:* +17 to hit, reach 20 ft., one target. *Hit:* 19 (2d8 + 10) bludgeoning damage.
***Frightful Presence.*** Each creature of the dragon's choice that is within 120 feet of the dragon and aware of it must succeed on a DC 21 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the dragon's Frightful Presence for the next 24 hours.
***Breath Weapons (Recharge 5-6).*** The dragon uses one of the following breath weapons:
* **Cold Breath.** The dragon exhales an icy blast in a 90-foot cone. Each creature in that area must make a DC 24 Constitution saving throw, taking 67 (15d8) cold damage on a failed save, or half as much damage on a successful one.
* **Paralyzing Breath.** The dragon exhales paralyzing gas in a 90-foot cone. Each creature in that area must succeed on a DC 24 Constitution saving throw or be paralyzed for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

***Change Shape.*** The dragon magically polymorphs into a humanoid or beast that has a challenge rating no higher than its own, or back into its true form. It reverts to its true form if it dies. Any equipment it is wearing or carrying is absorbed or borne by the new form (the dragon's choice).
 The dragon can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The dragon regains spent legendary actions at the start of its turn.
**Detect.** The dragon makes a Wisdom (Perception) check.
**Tail Attack.** The dragon makes a tail attack.
 On initiative count 20 (losing initiative ties), the dragon takes a lair action to cause one of the following effects; the dragon can't use the same effect two rounds in a row:
* The dragon creates fog as if it had cast the Fog Cloud spell. The fog lasts until initiative count 20 on the next round.
 The region surrounding a legendary silver dragon's lair is warped by the dragon's magic, which creates one or more of the following effects:
* Once per day, the dragon can alter the weather in a 6-mile radius centered on its lair. The dragon doesn't need to be outdoors; otherwise the effect is identical to the Control Weather spell.
* Within 1 mile of the lair, winds buoy non-evil creatures that fall due to no act of the dragon's or its allies. Such creatures descend at a rate of 60 feet per round and take no falling damage.
* Given days or longer to work, the dragon can make clouds and fog within its lair as solid as stone, forming structures and other objects as it wishes.

If the dragon dies, changed weather reverts to normal, as described in the spell, and the other effects fade in 1d10 days.