So I've been DM-ing the Curse of Strahd campaign for quite a while and the group has finally made it into the late game. I was looking at the possible ways the campaign could end and was disappointed with what the book gave me. And I think my party agrees.

Every member in my D&D group are very clever, very competent strategists. They've been doing, not just very good strategic choices in combat, but even in the process leading up to said combat. They've encountered Strahd about 3 times now, 1 of which Strahd had to run away despite the group being level 4, and another in which they actually killed him and sent him back to castle Ravenloft. And they were level 6! (Nearing 7.) I once asked for their predictions on what might happen at the end of the campaign. They all had very interesting ideas going around a singular idea: Strahd von Zarovich won't be the final boss.

I feel that after more than a year in the making of this epic story, having the ending being "you beat the bad guy and get out of Barovia to continue adventuring" just doesn't feel right. First of all, even though Strahd will have lair actions and the heart (which honestly by the time they get to castle Ravenloft they are exploring every nook and cranny before getting into that boss fight. So he wont even have that.) And even with the help of the three brides, Strahd just wont pose enough of a challenge to my now level 8 (soon to be 9) characters. On top of that, having Ezmerelda D'Avnir just leaving the party to stay in Barovia just feels so much against her character, or at least what she has become in my campaign. And on top of it all, it doesn't even end happy! The mists and Strahd just come back and the characters go back to the way they were when they were level 1! I mean I see why of course, For 'new adventurers to arise' and all that. Yeah, well they can do that in a different universe.

Anyways, the ending is dawning upon us and I must think of something. I've already welcomed homebrew into the equation as I've already added many homebrew elements into the campaign so any homebrew Ideas I'll welcome with open arms. Honestly, ANY IDEAS I'll welcome with open arms. Also feel free to ask about how the campaign went. It truly is a great story, and very unique I'm sure to other peoples play of Curse of Strahd. Not to mention I've yet to see any other curse of Strahd players on D&D beyond so please make yourself known!

How close are you to the end? What have the party done, or not done, in Barovia? You said you introduced homebrew elements, are they story elements? What are they? We can't crowd source a satisfying ending to a campaign without knowing the plot strings that have been laid out. Frankly, it might be hard to pivot to a different ending all together if you haven't been laying the groundwork for something else - a "plot twist" as the ending only works if there's a reasonable chance that the party may discover it beforehand. Otherwise it might feel to the players like you're pulling a DM card and changing things for no reason. 

That was the pessimistic take. For a more positive take: can Strahd have a secret reinforcement? Maybe there's more that the group needs in order to escape, rather than what's in the book. Have you spoken at all in-game about the Dark Powers or the fact that the mists are part of a larger whole of different Domains of Dread? Maybe that can be used for something. 

Ok, I'll lay the whole background out for you. So, when they started the campaign, Bib, the fighter, was bitten by a werewolf. Normally this would've been easy to heal with a scroll of greater restoration, however they found out whatever he was bitten by wasn't normal and couldn't be healed by normal means. They then tracked the werewolves into the mists and that's how they ended up in Barovia in the first place. This was my first homebrew element. To make the story more interesting, An NPC told them that they would have until the next full moon (30 days) to find a cure for Bib, or else he won't be able to contain whatever is going to happen to him. This makes it more interesting than the motivation of 'just wanting to get out.'

Also, While the characters have had different interactions with Strahd and heard from many different perspectives who Strahd is, (for example: Ezmerelda D'Avnir describes him as a conniving villain why Arrigal says he's a nice guy who does what is necessary for Barovia,) It still has not been confirmed Strahd is Evil or Good. In fact there is even a bit of a divide between the half of the party that thinks that he is evil for sure and those that say it is up for debate. The characters only know a small amount of his backstory as they do not yet have the Tome of Strahd, but they know that a long time ago he conquered the land and it was going well until he became a vampire. They don't know yet how he became a vampire but they know there was some kind of scandal with a girl.

As for what you were saying, I feel like they have enough time left in the campaign to learn about the dark powers that gave Strahd his Immortality. They have not yet gone to Amber Temple, but it is on their list of things to do, then they will learn about the dark powers. But I have foreshadowed to the dark powers a few times, so if the new and improved ending is revolving around that they could surely figure that out come time to fight Strahd for the final time. In fact the more I write about that last part the more Ideas I have. Perhaps, right after Strahd dies the dark power that gave Strahd his power keep the mists going and embodies itself into a physical form and you fight that, and that way if they kill that Strahd permanently dies. Or maybe it takes the body of KING BAROV as a vessel...too many ideas to write.

By the way, thanks for writing back. I've been doing D&D for a while, but I've only started using this website recently so it's great to meet other DM's or players that are as enthusiastic as I am! Anything you want to clarify on or if you want more details on the story so far I'd be happy to do so.

If you have access to Flee Mortals, there's a great Strahd replacement boss in there: Count Rhodar von Glauer

Besides that here is my plan for my level 11 min-maxers (they cleared nearly the entirety of the map and I'm not good at resisting "Do we level up?" so I've just amped the difficulty of everything else up):

I think a CR 19 after a dungeon crawl should be more than enough challenge for them. At level 10 they successfully beat a CR 14 Beholder like creature (Flee Mortals' Xorannox as a stand in for the demi-lich Exethanter) and a CR 16 C'thulu-esque entity right afterwards (Flee Mortals' Ithu’rath as The Avatar of one of the other Gods trapped in the Amber Temple). They demolished Exethanter while barely expending any resources (thanks to Paladin aura in a small room among other things) and I wanted to put more pressure on them to feel the Temple was still an evil place that they couldn't slow down/long rest in and had this back up prepared in case they were lingering too long.

I'm planning on running Strahd fleeing through the castle each time the party takes him to ~half his hit points, sooner or later based on which side is getting destroyed. They'll first encounter him at the top peak of the tallest tower, descending into a final encounter in the crypt chasing him through the Castle itself, with maybe an encounter in between if the party is healthy enough after the first encounter (no more than 3 encounters with him total, don't want it to be a 7 hour fight).

More ways I'm planning on amping up the encounter:

• Strahd can phase through walls and the floor and will heal most of the way in between each encounter unless they are really clever in trapping him.
• Make it clear there will be no long resting in the Castle. It just doesn't make sense that it would be allowed by the threats in the Castle.
  • Short rests will be allowed if the players come up with a good enough excuse for it (i.e. we barricade the doors, have the companions/army we brought with us hold the line so we can recuperate, etc.) 
• If the party has scoured the Castle and killed all the Vampire brides, then they'll hopefully be lower on resources.

Encounters before facing Strahd:

• These serve as "trash mobs" that will allow the players to feel powerful and be able to flex all of the resources they have gathered. It's important IMO for the players to feel like all of their work adequately prepared them and made them stronger. Cleaving through hordes of vampire spawns/zombies will hopefully be cathartic fun for them. But also, any spell slots/health/items I can whittle away is a good thing.
• Again, Flee Mortals comes in clutch with it's "Minion" rules, allowing you to stack up a bunch of enemies in one "target".
• Inspired by BG3, the players will be able to "spend" a companion/group to skip any one of these side encounters and push further on without them.
  • Some may die, but that is a sacrifice I'm willing to make.
• I have one particularly exciting encounter with Rahadin (as a full Vampire from Flee Mortals), Ludmilla (as Argan Rael [i.e. wizard/spellcaster] from Flee Mortals) and the one previously deceased party members reanimated corpse planned for when they arrive. This will be personal seeing the and I'm interested to see if they are baited into an immediate fight or not.
• Anastrasya will be leading a horde of vampire spawn and zombies (as a full Vampire herself from Flee Mortals).
• Volenta will attempt to assassinate one of the party members as they're exploring/taking a short rest, supported by a cadre of Vistani assassins
• The Abbot from the monastery could show up if Strahd is getting destroyed and I feel he needs the support.
  • In my version he was sent by his "good" God to ensure Strahd remained in this realm, and that no other Dark Entities in the Amber Temple got out. He has since been corrupted by the land and his frequent visits to the Amber Temple, but holds to the idea that he is doing "good" by keeping Strahd and everyone else trapped here.
• Werewolves are not getting involved because of internal strife that the party set up earlier.
• If not encountered on the way, all the extra encounters can serve as complications that Strahd can throw at them while he flees and heals, still draining resources from players.
• Not all encounters with Strahd have to be combat, if you want the chase sequence or any one of these to be a narrative/roleplaying encounter that may help break up the monotony of combat for players who don't love combat as much as mine do.

The Big Showdown and the Bigger Showdown

• While I initially laid on pretty thick that the heart was important during the parties first foray into the castle (and my group zealously takes notes), this time I'm not going to hint at the heart being pivotal to healing him, just a heartbeat or two mention as they're exploring the rooms, and I'm going to allow Strahd to "die" while the heart is still in tact.
• I've also built up Vampyr and will be running a final binding ritual after the party slays Strahd and releases the essence of Vampyr.
  • The party is pretty convinced Strahd was evil long before his pact with Vampyr, I never wanted to portray "He was only bad because he was possessed by an evil god," so based on the groups conclusion I think it's fine to have a final-final encounter with the bigger bad behind the curtain, not robbing them of their heroic moment and allowing them to maybe even do more than "what they came here for" in slaying "Dracula".
  • My inspiration for this is going to be a big JRPG style "final phase" of the boss fight, and will happen in the same session, fast forwarding the party straight to it after they kill Strahd. If the Strahd fight takes to long, this will be run as a narrative encounter and not actual combat, with just a bunch of die rolls as each player decides how they're helping conduct the ritual.
  • Otherwise, I'm running the Flee Mortals Kraken accompanied by hordes of zombies for 5 rounds of combat and they just have to survive
  • One of them each turn will need to sacrifice their turn to conduct the ritual, ideally a different person each turn so they feel like they're all finishing it "together".
• If the Heart of the Tower hasn't been destroyed, Strahd without Vampyr will resurrect in the epilogue, keeping it vague on if he is still a vampire or not, just a simple "after credits" teaser.
  • This keeps it in line with the OG ending that is narratively woven into the whole campaign (Gulthias tree coming back, Tatyana cycle, souls never being able to leave, etc.). And while they ended the "big" threat, traces of the evil remain, keeping it hopefully satisfying for the players yet also a modicum of extra "Horror" to end it.
  • If they decide to shatter the Heart, then great job they get the happy ending that they more than deserve for overthinking everything!

TL;DR: Use the Castle Ravenloft's full capabilities and cast to drain resources from the players, in addition to giving them a hopefully satisfying multi-phase boss fight. Them "beating" Strahd in each encounter results in him going from Nonchalant -> Serious -> Seething Angry -> Surprised to be defeated.

I love the whole thing, And I love the idea of Vampyr being this Kraken-like creature that they have to destroy together!...
Except I do not, in fact, have Flee Mortals.
I would even get it, but I haven't been using it for the rest of the campaign like you have. It sounds to me like your party has been fighting monsters from Flee Mortals throughout the campaign making them particularly high level. My party will likely be level 8 or 9 by the time they get to the final encounter. Despite this, I have a feeling a CR 17-19 would be an appropriate challenge considering how well my party has been doing against things 'their level.'

I might actually be able to create a Cthulu or Kraken boss myself by scratch, though. So I'll certainly consider what you are saying as a concept.

It seems to me like you're still in the middle of your Curse of Strahd campaign yourself. I love hearing more about other peoples experiences! If you'd like, I'd love to hear how your campaign went out compared to mine, especially because you have Flee Mortals, which is something I know very little about. And also, thanks for taking the time to write that whole thing to help me, it's really appreciated.

So I got Flee Mortals as they were going into the Amber Temple and started integrating it there, so it's only been a few sessions but I really appreciate the way that they built monsters in it! It's essentially just 5e monsters but given more flavor through what they can do. Particularly the boss characters normal Legendary Resistances are usually replaced with a more interesting mechanic (i.e. as the Beholder uses it's Legendary Resistances, it loses random eyes up to a few times). Also gives monsters more interesting Action/Bonus Action/Lair Action's, so there's a bit more dynamics naturally in the fights.

The players are on there way towards Castle Ravenloft, so me writing this up was actually a bit of prep as well :D Final session is happening this weekend and I'm pretty pumped for it.

So far, our campaign as a whole has been lovely. 

The fortune was rigged by me to get the players to Argynvostholt, Krezk, and Amber Temple, Strahd at the top of his tower, Ezmerelda as the companion. Rigged it with sleight of hand though, shuffled the deck in front of them and stacked it so my players will hopefully never know.

The flow up to this point was: Death House -> Barovia -> Old Mill -> Vallaki -> Argynvostholt (1 player died to the big stone wall & ghost skeleton trap, I gave him the chance to come in as Godfrey and he accepted, so Godfrey is now a PC) -> Vallaki -> Yester Hill & Winery -> Vallaki -> Castle Ravenloft Dinner -> Vallaki -> Krezk -> Amber Temple -> Swamp & Baba Lysaga -> Vallaki -> Castle Ravenloft. Lots of fun interactions and side quests to do in Vallaki, and each time they would experience the fallout of their previous actions (i.e. when players decided to burn down the house of the Lady Wachter AND the coffin makers shop in the same week, with a couple of neighboring houses catching fire, some townsfolk decided to follow suit and started witch hunts against their neighbors, the party came back and they had a cult following responsible for burning down around 1/4 of the town that they had to try to defuse).

Pretty standard integration of most of the stuff from the core book with a sprinkle of Dragna Carta, MandyMod and Lunch Time Heroes, and other personal homebrew stuff as I felt it was appropriate. Not too much because I didn't want to ruin the pacing too much, and I wanted the characters to feel like they were "completing" things and not stuck here for 10 in game years.

My players and I are all big fans of story games with complex deep lore (was playing Elden Ring around the time I was doing a lot of my prepping) and wove some extra narrative around the Dark Powers/Gods/Vampyr, as I wanted there to be some actual reason/purpose/rationalization for how/why Vampyr and the Dark Powers were bound in the Amber Temple in the first place. So in my world Vampyr and 2 other Dark Gods (Tharizdun: a reality shifting Cthulu-esque god, the other just mysteriously called "The Unnamed" and described as "A God of the Unknown") were "pinned" to the Amber Temple by a cadre of 5 Gods. In order to do this the Gods betrayed one of their own: The Morninglord – Lathander -- so that appropriately thematically "Dawn would never again rise in this land". So his body/essence IS the Amber Temple in my rendition, and as one of my player characters is now Godfrey, a revenant knight of the Order of the Silver Flame (which worships the Morning Lord), finding this out from a convenient lore dump from the Abbott of the Krezk Monastery (who was sent by one of the other 4 Gods to make sure the seals still held after Vampyr was "released"). It also helped tie in the reason for the Order of the Silver Flame being founded by Argynvost to defend the Amber Temple, as they worship Lathander.

In D&D Pelor is also a God of the Sun, and so he of course was in the cadre of 5 (Kiri-Jolith, Onatar, Selune, Pelor and Lathander), and as my Barovia and Strahd are from Greyhawk it aligned with having 2 different "versions" of the "Morning Lord". Strahd expanded his territory under the banner of the Morning Lord and was experienced by the players through the Interactive Tome of Strahd flashbacks we ran for a few sessions. These flashbacks were further modified a bit from the lore I enjoyed from I, Strahd.

I depicted Pelor as a Sun God that's more 'passive', whereas Lathander was more 'aggressive'. i.e. the first warmth of the sun vs. the burning of the sun over the horizon. Pelor would be fine with simply ruling during the day, Lathander is all about "burning away the night". Idk if I based this off of their actual in universe characteristics or I made it up, but it's worked out pretty well. A great roleplaying convo happenend b/w Godfrey and Father Lucian in Vallaki about who "The True Morning Lord" was and what he would want for the people of Barovia.

I love the idea of my players are accomplishing something (killing Strahd and banishing/sealing Vampyr) that they know a bunch of Gods had to commit a great betrayal to do.

Oh no way, this weekend!? That's a climactic weekend for sure. You started using Flee Mortals quite late it seems, I could probably actually use it then.

Reading this I realize that we are incredibly similar. Our flow of the game looks quite similar to yours, except with not as much visits to Vallaki and they never went to castle Ravenloft yet.
Me and my party love lore too (and I have in fact also played Elden Ring and all Souls-borne actually.) But I absolutely LOVE your whole thing with the three dark powers. Beautiful worldbuilding. And super convenient Godfrey joined, right! You definitely inspired me to write out some lore about the dark powers too, but without copying you. Anyways, It seems like you guys had a delightful campaign so far, hope you have fun with your last session!

I can see that we also had very different campaigns in a way, as my players did not plan to stay in Barovia more than 30 days (because werewolf bite.) And I know for a fact you didn't do some of the crazy stuff we did in our campaign. It's so fun to actually know how other peoples campaigns can go, and it seems like you guys had too good of a time. Once again, thanks for taking the time to share, and you really inspired me to amp up the lore a bunch.

Oh and by the way, you definitely got a Nat 20 on Slight of Hand check IRL.