Betrayer

Brave. The Betrayer has advantage on saving throws against being frightened.

Cold as Steel. Whenever the Betrayer lands a weapon attack, the weapon deals an additional 1d6 cold damage (included in the attack)

Multiattack. The Betrayer makes two melee attacks.

Greatsword. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 4) slashing damage and an additional 4(1d6) cold damage. 

Heavy Crossbow. Ranged Weapon Attack: +3 to hit, range 100/400 ft., one target. Hit: 5 (1d10) piercing damage and an additional 4(1d6) cold damage.

Breath Weapon (Recharges after a Short or Long Rest). The Betrayer breathes put a 15 ft. cold of cone. Each creature in the cone must make a DC 14 Constitution saving throw taking 4d6 cold damage on a failed save or half as much on a successful one.

Leadership (Recharges after a Short or Long Rest). For 1 minute, the Betrayer can utter a special command or warning whenever a nonhostile creature that it can see within 30 feet of it makes an attack roll or a saving throw. The creature can add a d8 to its roll provided it can hear and understand the Betrayer. A creature can benefit from only one Leadership die at a time. This effect ends if the Betrayer is incapacitated.

Cold Blooded (Recharges after a Short or Long Rest). The Betrayer forces one creature within five feet of it to make a dexterity saving throw or make a DC 14 Dexterity saving throw. The creature suffers 2d10 cold damage on a failed save and half as much on a successful one.