Warmth Thief

Aura of Warmth Stealing. At the start of each of the warmth thief's turns, each creature within 5 feet of the warmth thief must succeed on a DC 16 Constitution saving throw or take 7 (2d6) cold damage. The warmth thief regains hp equal to the single highest amount of cold damage dealt.

Cold Physiology. A warmth thief can't abide constant warmth. Each hour it spends in an area with a temperature above 40 degrees Fahrenheit, the warmth thief must succeed on a DC 15 Constitution saving throw or suffer one level of exhaustion that can't be removed until it finishes a long rest in an area with a temperature below 40 degrees.

Multiattack. The warmth thief makes two freezing claw attacks.

Freezing Claw. Melee Weapon Attack: +8 to hit, reach 5 ft., one creature. Hit: 7 (1d6 + 4) slashing damage plus 14 (4d6) cold damage. The warmth thief regains hp equal to half the cold damage dealt. The target must succeed on a DC 16 Constitution saving throw or be chilled for 1 minute. A chilled creature takes 7 (2d6) cold damage at the start of each of its turns. A chilled creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. A humanoid slain while chilled rises 24 hours later as a chill haunt, unless the humanoid is restored to life or its body is destroyed.