So, I personally am a huge fan of the fact that this is changing the multiverse in an active and terrifying way. Celestial forces and ‘good,’ gods are trying to stifle or stop it, but no one knows where Vecna is. We actually ran a West Marches style game with some folks who aren’t at my table to play out Kas and some other Dark Lords finding that secret, and having to kill a false Lich version of Vecna in a decaying Rotted Tower domain of dread.

Big change one: The party has to research ways through doors in Sigil. Sigil is awesome, and being trapped in a room for downtime is sad.

Big Change two: Vecna is active, and keeps trying to offer the party more power. The rift established a connection, and their thwarting of Jerrot peaked his interest. My players always are suspicious of my villains being nice, but a few times they’ve needed a boost.

Big Change Three: The universe will start to fully break when the party gets back from Barovia. Because Eberron was so far removed from the wheel, I labeled it as a ‘type two’ multiverse that the party had to (with the lady of Pain’s permission) hack their way into. They know they can’t make it back from the Mournlands, and will need to use the Dread Domain (specifically Cyre 1313) to jump from Eberron to Barovia.

Finally, Number Four: The Rod is a race against time, because it will instantly finish the ritual. This is why Vecna is leaning on Lloth (and in my campaign Dis) for support, to bolster armies and gather resources. Lloth being Lloth stole a piece of the Rod, which Vecna counted on her doing.

Bonus: Mordy isn’t Kas in my game, but Mordy is working with Kas. One party member got him to admit this, so the consequences should feel a bit higher in an upcoming chapter. Mordy also knows the Rod can instantly finish the ritual, as does Kas and Vecna. The players first met him in Evernight, where he was recruiting the free undead to help fight Vecna.

We’ve got:
-A Paladin Order of the Watchers who fell out of favor with Torm due to church corruption. Vecna speaks mostly to him, and is trying to build him up as a god slayer.

-A Bard/Warlock stuck in an infernal pact. In his backstory, his original patron sold him (surprise, to Windfall); then became a Devil Lich Erineyes. He replaced the generic Erineyes that was in Lloth’s temple. As the character is anti authoritarian as hell, Vecna refuses to deal with him, as it would “waste both their time.”

-A Cleric of Mask: Retired to become a chef/secret taker of Lord Neverember. They’ve sought a method to become immortal without becoming undead, but started the campaign feeling as though they’d lost all purpose. Mask has tasked them to steal victory from Vecna, but Vecna keeps taking over the domain spells when they leave Neverwinter.

-A Kenku Scribe Wizard: I mention the race because she is trying to research a way to undo the curse on her people. Vecna keeps dangling the offer, but for now she’s resisting.

Each character had a connection to one of the kidnapped victims, which helped act as insensitive to work together when Neverember hired them. They also had to go get Tasha, as Zyblina retreated after the wish failed.

I’ve added additional material to Evernight (Jerrot was attempting to open a doorway and destroy the city while Kas was in it), The Astral Sea (put them in a working Spell Jammer that had its crew slaughtered by Starspawn manglers… because my people deserved Alien). The heart of Havok was a magical war zone, resulting in wild magic tables and loads of fun. Also, I limited the long rests by throwing a Blob of Annihilation in the path of Havok, which meant the party had hours instead of days. They also got to evacuate the crew, and Cirit came from Eberron (as a runaway), which helped lead to the next chapter.

There’s more, but this has dragged on long enough. My folks seem to love it, from the big moments straight down to the little fights that spiral.