In my home campaign, I've build up this concept for the big bad boi, who I call the Six-Eyed Beast; a Nightwalker, who was made especially  powerful when an ancient evil empire sacrificed people to it with a forward promise that they would manifest it into the Material Realm. This last point has nagged me - I don't know how this should've happened. The gist of it is that this ancient empire was completely consumed by the Beast and its minions, leaving an eerily empty continent that the humans, dwarves and halfings that live there now didn't know it had been inhabited before then.

My D&D lore knowledge isn't that deep, so maybe you guys can help me - would it make sense to have a Wild Hunt-faction but from the Shadowfell? Who would be a part of this "Fell Hunt", what creatures would it be? I know I know, "It's my game so I can do what I want" but I'm kind of stumped.

All I know I want is that the Fell Hunt (or whatever I call it) create eternal winter as life literally gets snuffed from the air, while the world is assailed by enormous amounts of... Something undead-related. Right now, one of my players have the Beast as his Patron and it's an Undying Patron pact.

Any ideas? Cool stat-blocks I should be using or concepts to steal from?

Consider looking for creatures with sunlight sensitivity as a starting point Flying Horrors and things like that, that are hunters by nature, coupled with shadarkai as mentioned above.  Also consider reskinning some devils or demons for use, like Cambion.  Gloomstalkers would be in a similar vein.

Are you looking for who or what would be the leaders of the hunt, or just general ideas about the idea?

I think it’s a great idea. Maybe the Shadow Hunt raids the Feywild to hunt down an eladrin princess/prince who has earned the enmity of the Dark Powers and your PCs have to stop it (and maybe they need to find the “real” Wild Hunt first and bring back the Hunt Master’s horn to help them in their quest).

Good luck 😊

Like others have mentioned, Shadar-Kai (pronounced shuh-dahr kye) exist if you want to alter their lore a bit for your world, as they follow the Raven Queen in 5e.

If you want some other ideas, you could possibly use Kenku, who are a fallen race of crow/raven people. They used to have a master who they betrayed, who took away their voices and wings. There are many suspects for this master, one of them is the Raven Queen who dwells in the Shadowfell. 

If you want some unique ideas, I created a race of people called the Vezyi (pronounced veh-zyee) for my homebrew world, who are kind of undeath-touched grey-skinned humanoids whose society is based around worshipping and serving Vecna throughout their multiple lifetimes. 

If you want other creatures that you could use, shadow mastiffs, and lots of monsters from Mordenkainen's Tome of Foes work for Shadowfell campaigns, as well as gloomstalkers, shadowghasts, and many others. 

Thank you for all your contributions!

I'm going to use the Shadar-kai as the main force of this Fell Hunt (or whatever I'm going to call it); originally I wanted someone imposing and unknowable but seeing the stat-blocks of the Gloomweaver and the Shadow Dancer, it struck me just how well they fit the lore I'm going for. Additionally, having faces on the enemies my players will face is going to be more interesting for them, and probably me as well.

So, here's the lore I'm at right now: There is this extra-powerful Nightwalker that wandered the world back when the world was younger, and, rather than just consuming life as it went, it began to learn about mortals and the world around it. It become truly sentient, learned magic, history, speech and more, before being bound in a temple made for it by a set of ancient heroes. Here it waited, corrupting what it could find and those that contacted it. Many, many years later, a kingdom of Gnomes unearthed it and their ruling caste began to worship it, becoming Warlocks for it, which spread its influence over the Material Realm. The Gnomes, now the Dark Gnomes, spread their cruel empire over the continent but still wanted more.

The Nightwalker promised the world to them if they unleashed it, which they did - And it immediately consumed them, their empire and all other life as it went on a rampage, directing Nightshades, Nightwalkers, Shadow Mastiffs, Shadowghasts and more to consume all they could find. The Gods intervened and banished the Nightwalker to the Shadowfell, where it remains in chains today, guarded over by the Raven's shadar-kai minions (in my world, the Raven Queen is simply known as the Raven; she cannot manifest her elven form outside her castle). However, the Nightwalker's corruption is insidious, and slowly a secret cult emerged among the guarding Shadar-Kai. The Nightwalker had a plan - It wanted to become the new god of Death, of the Shadowfell, and so be able to consume all life that dies for the rest eternity.

Aaaand this is where my players come in. The Nightwalker (Name pending...) exerts its influence into the Material Plane, using agents and Warlocks to create a new Fell Hunt to once again consume the continent. One of my players are a Warlock dedicated to it, one is a Cleric dedicated to the Raven and one is one of the few Dark Gnomes who realized the folly of their actions, bound as a soul to a Warforged that the Gnome Empire used back in the ancient times.

I'm looking forward to sending Shadar-Kai after my players, and horrifying them with the power of the Nightwalker!

Quote from Lyxen >>

Are you using the Nightwalker from MToF ? That and its companions nightshades (nightcrawler and nightwing) were amongst the favourite monsters of BECMI, and the last two were sadly never really reintroduced in AD&D / new D&D editions as far as I know.

But that is an idea, I'm probably going to homebrew them very soon... :D

 The very one! I loved the idea of something so alien that is technically not even "Undead" - it's just... Death, in the flesh. Where most of "death" in DnD is just a step in a new direction for your soul, the death the Nightwalker represents is pure oblivion; ceasation of existence. That is horrifying to me! What if a creature like that decided to take power, to make plans and to be ambitious? 

I thought the other Shades were already in the MToF, but maybe not... I'll look at some homebrew for them as well, but I'd love to see yours as well.

This sounds super legit.  You got your creative juices flowing.  Could see this being quite aninteresting trip.

Quote from Lyxen >>

Quote from Jakebit >>

I thought the other Shades were already in the MToF, but maybe not... I'll look at some homebrew for them as well, but I'd love to see yours as well.

 

Here they are... :D

Jiminy willikers Batman, that's some nasty abilities! Removing magical items, rendering potions unusable and more! I'm not used to DMing high-level campaigns but it seems cruel to me!

See if you can find a copy of The Compendium of Forgotten Secrets - Awakening  Genuine Fantasy Press 

edit: official free version for download here: https://www.genfantasypress.com/about-the-compendium

Shadar Kai are really cool as NPCs or as playable characters. No campaign in the shadowfell is complete without them.