Fogborn Reaper

There are times where the veil between life and death thins. The Fog is a manifestation of this thinning barrier. A ship caught in it out at sea ends its voyage a crewless ship. Rarely there are those who emerge from it, forever changed by the visions they see within its mists. A fragment of the Fog remains with them and some learn to harness its power. Able to call forth a manifestation of this Fog, while within it they become a deadly master of its domain.  

Pierce the Veil

Your harrowing experiences in the Fog have hardened your nerves and heightened your sense. You gain advantage on saving throws against being frightened. In addition, you are able to expand your senses and tell if anything has died in the area you are in within the past week.

Fog from Beyond

Starting at 3rd level, you can call forth a manifestation of the Fog. As a bonus action you create up to a 20ft sphere of the fog centered on a point within range. The area is heavily obscured. The area lasts for 1 minute or until a wind of greater speed (10 miles per hour) disperses it. The maximum size of this sphere increases by 20ft at level 7, level 13, and level 19. 

While in the fog, you ignore the disadvantage on attack you would normally suffer in a heavily obscured area. You also can use your sneak attack when you attack an enemy that is within the fog. 

Disaster's Clutches

The fog you manifest thins the veil between life and death further. Visions of death begin to show through. When an enemy creature attempts to leave the fog they have to succeed at a Charisma saving throw (DC 8 + your Dexterity modifier + your proficiency bonus). On a failed save, the creature is unable to leave the fog as visions of death plague it, forcing it to stay.   

Grab the Mists

Your control over the fog continues to grow. When you manifest the fog, creatures of your choice no longer suffer disadvantage when making attacks within the fog. Additionally, you can make attack against any creature within the fog as if you were adjacent to them.

At the end of each of your turns you can move the fog up to 10 feet.  

Calamity Personified

Beginning at 17th level, you become nearly one with the fog. Once per long rest, you can use your action to make a sneak attack on every creature of your choice within the fog. Additionally, you can choose to change the damage type of your sneak attack to necrotic or cold damage.