The current arc of my campaign ended in epic fashion. It's a modified version of Storm King's Thunder where the Zhentarim have been the power secretly manipulating the giants. Manshoon had seized Blackstaff Tower and the player characters assaulted it with the help of multiple NPC allies. (Spoiler: Most of the NPCs died.) The characters are 15th level.
This session was the final showdown with Manshoon. It started in Blackstaff Tower and then literally went to Hell and back. It featured a lot of big character moments and unexpected twists, so I guess the simplest way to tell this story is by recapping what happened with each character.
Elf arcane trickster rogue: In the previous session, he and several NPC allies destroyed the laboratory where thousands of Manshoon clones were kept in statis, thus clearing the way for the destruction of the true Manshoon. When the session started, he arrived in the teleportation circle at Blackstaff Tower. Soon, he was fighting waves of Zhentarim reinforcements, including a longstanding mini-boss. He landed the killing blow on the mini-boss.
Aasimar vengeance paladin: In the previous session, he had been teleported to the other side of Waterdeep. Manshoon was in possession of the Blackstaff itself, which he used to awaken the Walking Statues of Waterdeep. Those statues were now rampaging across the city, destroying everything in their path. Rather than fight the Statues, the paladin decided to return to Blackstaff Tower and confront Manshoon. He unfurled his radiant wings and flew across the rooftops to Blackstaff Tower. Once the tower was in sight, he used dimension door to teleport inside. There, he found his mentor, the high priest of Ilmater, dead. Alongside him was Vajra Safahr, the legitimate wielder of the Blackstaff, also dead. Both at the hands of Zhentarim agents. The paladin killed two of the Zhents, then used revivify to bring the high priest back to life.
Halfling lore bard: Actually, the halfling's soul is trapped in Hell. But none of the characters know that. Controlling the halfling's body is the soul of his deceased rival, a vainglorious bard pledged to the Archdevil Glasya. (More on Glasya later.) The halfling's ambitious brother is in league with the Zhentarim and now rules Waterdeep as their puppet Open Lord. Like the paladin, the halfling had been teleported across Waterdeep, into the path of a rampaging Walking Statue. Taking cover, the halfling used a teleport spell to travel to Waterdeep Palace. He entered his brother's private chambers. Charmed him. Had him sign over his powers to the halfling. And then shoved him off the balcony to his death. It was a big time Cersei Lannister play that shocked the other players. They still do not realize that the halfling is under the control of someone much more evil.
Tiefling shadow sorcerer: She is the daughter of Manshoon and Glasya. Glasya wants her to kill Manshoon. Manshoon wants her to kill him, too. But, once he's dead, his soul will transfer into the Blackstaff. From there, he can mentally control the sorcerer. By day, she will be the new master of Blackstaff Tower. By night, she will secretly rule the Zhentarim. But in truth the soul of Manshoon will be the power behind the throne. Together, they will rule the Realms as father and daughter! Well, the sorcerer had other plans. When her companions were forcibly teleported out of Blackstaff Tower by Manshoon, she was left alone with him and his last two surviving clones. Approaching Manshoon, she hit him with a plane shift spell. Together, they arrived at Glasya's palace in Hell. Mother and daughter now had father in their clutches. Cursing them both, Manshoon struck Glasya with the Blackstaff. Retributive strike! As the staff exploded, the sorcerer was sent hurtling across the multiverse. She awoke under gray skies, floating in the dark waters off the shore of an isle of black stone. On the isle was a single lonely tower. Intuitively, she knew she was in the Shadowfell. She entered the tower -- Manshoon's private sanctum. Following a trail of blood, she found a dying Manshoon on the floor of his arcane library. "What are you waiting for," he rasped. "Finish it!" And she did...with a firebolt to the face. Moments later, her half-brother Zorion appeared. An enforcer for the Red Wizards, he had loaned her a Staff of Power to combat Manshoon. In truth, he had used the Staff to track her movements...and she had led him straight to the vast power of Manshoon's arcane sanctum. His masters in the Red Wizards would be pleased. Too weak to fight Zorion, she fled. But not before stealing Manshoon's Staff of the Magi and Robes of the Archmagi. Using the power of a permanent magic item to fuel her sorcery, she plane shifted back to Waterdeep. At Blackstaff Tower, the surviving Zhentarim immediately recognized her authority. They knelt and pledged loyalty to the new leader of the Zhentarim!
Human beast master ranger: This player was a no-show. His character fought the Zhentarim offscreen, away from the action. When it was all over, the ranger walked into the scene and said, "So what did I miss?" Ha!
So much happened so quickly that my players literally burned through or made obsolete the next three adventures I had planned. Months of content down the drain! It was glorious. My players made some big, bold, unexpected choices.
We're taking two weeks off from this campaign so I can figure out what happens next. I think I'm going to throw a big party with all the key NPCs that celebrates the PC's victory and frames up several adventure options for them to choose from.