So, I promised I'd come back and say how the players may have just started the Raven Queen in my homebrew.
I'm running my Masks of the Imperium, where each of the PCs are Mask Bearers - wearing some of the artifact level masks made at the height of the Imperium that chose the characters because of similar goals and are slowly waking up. Items that both bestow authority which is one of the themes of the campaign, but also are magic and grow with the character for a campaign where traditional loot & magic are rarer. About 40 of the known 110-ish Masks are "awake", and there are many lost Masks. The players know from Session 0 that the Masks actually way predate the Imperium.
Anyway, they need to get back to the Imperium fast, because the Child Empress they serve has been somewhat usurped (legally - he's used an obscure rule to become her regent and cut her off from power) by her great uncle. The deep seas preclude magic and they are on another continent so they can't travel to her by magic, but they can through going to an alternate plane.
They found a portal to the faewild (and that was a fun adventure involving Frost Giants, a dragon's lair, and priming a volcano to explode and barely making it out).
So they surface in a wooded pool, surrounded by the colors of autumn, bright butterflies, and a nigh overwhelming sense of peace and calm. They casually dry off, noting that the woldlife is not affraid of them and squirrel eat out of their hand and butterflies flock to them. They hear a regular clicking, and when they eventually follow it, they find a mad-seeming fae woman with a big bowl of butterflies she's eating with chopsticks. This squicks out the players. She introduces herself as Asdzaa Weaverwoman and she demands they bring her more butterflies to eat as they are hatching, and these are the wrong butterflies - we need the monarch.
After some crazy-sounding conversation, the players start asking the interesting questions and get a save vs. the illusion of this place. The butterflies are stirges and their clothes are all stained red because they have been feeding on the characters.
A frantic encounter happens against two (homebrew) stirge swarms, and then they work to keep the stirge population down while trying to find the "right" butterflies. They are able to rescue "The Monarch", a local member of the Court who styles herself The Lady of Butterflies and appears as a fae Monarch Butterfly hybrid, and her butterfly sprite warriors. She grants them a boon that they may call upon her once. But when asked how to move further, she is of this place and says to talk to the Weaverwoman.
The Weaverwoman's right eye grows eight legs and pops itself from her skull as a black spider, and her body deflates to an empty set of clothing. She quickly weaves a bridge and when the party gets on it from their vantage it is a long and winding wooden bridge. I'm really playing up how the faewild is different. The eladrin was able to figure out fromt he unchanging dusk that they weren't in a domain of the Autumn Court, but rather of the Gloaming Court.
More fae weirdness but this is running long. Eventually it brought them to a cottage with two fae in it, a brillantly plumed "Mistress of Skies" and a dark feathered "Raven Harbinger" who will not speak directly to them, only the Mistress. (One player immediately called out "if one's good and one's evil, my money is on the dark one being good". Must remember that later to subvert both the trope and his expectations.)
Anyway, they were able to convince them to help, which would involve waking a friend of theirs from a thousand year slumber a different fae had put them under. The Gloaming Court is known for manipulation among other things. So they party ended up having to convince these two to let them rescue their friend, as he had the knowledge, without realizing they were also performing that service.
Anyway, some of the characters notice the Raven eying the two PCs who keep their Masks visible, and ask if they had ever seen anything like it. Now, I knew I wanted them to come across two Masks in the faewild - one worn and one not - to see what they do. This was one of the places I seeded that there could be a Mask, and with that question she strode across and opened a hutch to show it hanging there. They were able to get from the Mistress of Skies that the Raven was unready to take it up. Going based on what they had observed of her our wizard gave an impassioned speech about the nature of bravery and fear, urging her to take it up. Two difficult persuasion checks later, she did.
The Mistress of Skies, happy for her friend, bestowed a gift on each of them - a cloak of elvenkind, but one that would deteriorate quickly outside the faewilds. Still, for a stealth mission to try to rescue the Child-Empress, that's a very useful gift.
Then they went to find the Slumberer. (They wanted his name, but were told that names have power so all go by titles, and they had no right to give out his name.) More fae weirdness as they went through a forested area. They avoided an elven knight, beguilded a patrol with their celebrity bard (she loved that), and found the masuleom of the Slumberer. They failed the riddle three times and a thunder trap went off, but they got it quickly past that. The Guardian showed up, an grizzled old satyr warrior. With a distraction, one character was able to slip inside, and avoided the trap inside. But on the slab was a Mind Flayer! However, our paladin is Oath of the Watcher, and had requested when switching to it (better fit than his original Devotion when Tasha's came out) that his Divine Sense was aligned with his Turning which I allowed. So he can't sense consecrated/desecrated areas, but he can sense aberrations and fey among other things. He did it and got fey. They woke him, and the form was also part of the curse, as he's normally a strikingly handsome Eladrin who slept with the local fae lord's wife.
They got him out, removed the curse, and then heard the airboard bays of hounds and the sounding of horns - the guardian has noticed the Slumberer is missing and has called the Hunt.
Nest session, the frantic flight to the realm of the Winter Court!
