Cold One

Legendary Resistance: Once per day, when the Cold One fails a saving throw, it may choose to succeed instead.

Aura of Cold. Cold ones exude cold in their proximity.  The area within 5 feet of a cold one is frigid, and all flames are extinguished within it.  Water within 5 feet of a Cold One is immediately extinguished.  If a melee attack with a weapon is made, and the result is a 1, the weapon is damaged and cannot be used until repaired by a craftsman.

Immunity to Damage.  Cold Ones are immune to all damage from weapons and physical blows that are not from Parthian Steel or Obsidian.  

Pass Without Trace.  Cold Ones leave no tracks or trace of passage in ice or snow.

Magic Resistance. The Cold One has advantage on saving throws against spells and other magical effects.

Raise Ice Wight: (1 Action). The Cold One raises one corpse of a human or beast that it can see within 120 feet as an ice wight.

Chilling Mist: A cold mist rises in a 200 foot radius around the Cold One.  In this area, temperatures drop.  Creatures in the mist must make saving throws each hour or suffer exhaustion from cold, instead of once per day.

The Cold One makes two ice sword, two icespear, or two slam attacks and one icy blast attack.

Ice Sword.  +8 to hit. Hit: 13 (2d6 + 7) slashing damage.  On a critical hit, in addtion to the critical damage, the target must make a DC 18 dex save.  On a failed save, the sword severs a limb from the target.  Label limbs and head and determine randomly.  If the head is severed, the target is reduced to 0 hp. immediately. 

Ice Spear.  +8 to hit. Range 60/120. Hit: 13 (2d6 + 7) piercing damage.  On a critical hit, in addition to the critical damage,  the target must make a DC 18 dex save.  On a failed save, the target is impaled, and suffers disadvantage on all attack rolls, dexterity saving throws, and skill checks until the spear is removed.  Removal takes one action. The target takes and additonal 2d6 points of damage when the spear is removed.

Slam . Melee  : +8 to hit. Hit: 13 (2d6 + 7) bludgeoning damage, and the target makes an opposed strength check with the cold one.  On a fail, the target is thrown back 1d6 x5 feet, and must make a Dex check (DC18) or fall prone.

Icy Blast . Ranged Attack: +7 to hit, range 120 ft., 1 target. Hit: 13 (3d6 + 3) cold damage, and the target must save or is slowed (Con save DC 18).

Parry.   Once per round, the Cold One can attempt to deflect a blow from an iron or bronze weapon by making an opposed attack roll with its ice blade against its attacker.  The Cold One decides this before the attacker rolls.  If the Cold One wins, it takes no damage.  If the Cold One wins the roll by 5 or more, the opponent's weapon shatters, unless the blade is Parthian Steel or Obsidian, in which case this has no effect.

The Cold One gains two legendary actions per round.

Attack: the Cold Once takes one of its attack actions.

Nimble Movement:  The Cold One can disengage and move up to 30 feet without provoking attacks of opportunity.