Stygian Conclave

There is one layer of the Nine Hells that greatly resembles the frozen wilds of the material plane, and that layer is Stygia. The frozen wilds of this layer are guarded by a conclave of rangers seeking to maintain this ecosystem and drawing upon the layers power and the power of Levistus.

Mark of Stygia At 3rd level, you can instill within your attacks the chill of Stygia. Whenever you make a melee or ranged weapon attack you can as a reaction mark the targeted creature for 1 minute. For the duration, attacks you make against that creature deal an additional 1d4 cold damage. At 8th level, this becomes 2d4 cold damage instead of 1d4. You can only have one creature affected by this feature at a time

Stygian Hunter At 7th level, you are familiar with the cold reaches of Stygia and have learned to ward against it. You gain resistance to cold damage and are immune to the ill effects of cold weather. Additionally, cold damage you deal ignore resistance and treats creatures with immunity as only having resistance.

Tomb of Levistus At 11th level, whenever you deal damage against a creature marked by Mark of Stygia you can choose for that creature to have to make a Constitution saving throw, taking an additional 2d4 cold damage and becoming encased in a block of ice and being considered restrained and stunned for 1 minute. A creature encased in ice this way can make a Strength saving throw at the end of their turns to break free. Once you use this feature you cannot do so again until you take a short or long rest. Image from PNGArts