Spectral Cloud

Attack rolls against the spectral cloud are made with disadvantage unless the attacker is within 15 feet of the spectral cloud or the spectral cloud is Incapacitated.

The spectral cloud can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) Force damage if it ends its turn inside an object.

The spectral cloud makes two Spectral Touch attacks.

Melee Weapon Attack +12 to hit, reach 10 ft., one target. 20 (3d8 + 7) Force damage plus 10 (3d6) Necrotic damage. If the target is a creature, it must succeed on a DC 20 Constitution saving throw, or its hit point maximum is reduced by an amount equal to the Necrotic damage taken. This reduction lasts until the target finishes a long rest. The target dies if its hit point maximum is reduced to 0.
A Humanoid slain by this attack immediately rises as a miniature spectral cloud (use the Specter stat block in the Monster Manual). The miniature spectral cloud acts as an ally of its creator but isn't under its control.

The spectral cloud emits intensely cold wind in a 60-foot line that is 10 feet wide. Each creature in that area must make a DC 20 Constitution saving throw. On a failed save, a creature takes 38 (7d10) Cold damage and has the Incapacitated condition for 1 minute. The affected creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. On a successful save, a creature takes half as much damage only.
If a creature's saving throw is successful or the effect ends for it, that creature is immune to this spectral cloud's Chilling Winds for the next 24 hours.