This story takes place a few years ago. I am part of a Pathfinder group that meets once a week, and despite some out-of-character conflict between myself and one other character, the group has run smoothly for years.
I joined the campaign well after it started, and the party was already level 8. The party was Siegfried the human Paladin of Sarenrae, Kai the catfolk rogue, Akatsuki the human Cavaleir, Akatzuki's blue dragon mount Mizuki, Robert the NPC human wizard, and Alinza the NPC human cleric who was built to be the party's healer.
And then, there was me. Juvia, the Kitsune Shadow sorcerer, daughter of Rixon, the head of the council on Nine-Tail Island, their home that was made up entirely of Kitsune sorcerers. The party met me while I was running from a giant bug, and after the combat ended, Juvia was allowed to join the party.
Most of the campaign, while interesting, does not partain to this story, so I will skip most of it. Two major changes that I will note, however, are that Kai was eventually retired to become a school master for the assassin school Shadow Hunt Academy, and was replaced by Hollow, a one-eared Kitsune who I'm still unsure what his class was. The second was that, due to me not getting much enjoyment out of being a Shadow sorcerer, the DM allowed me to change my subclass. With this freedom, I converted Juvia into being a Starborn sorcerer, and had much more fun with the abilities it gave me. The in-game explination for the sudden change in Juvia's bloodline powers was that the original Juvia had touched some object of unknown power, and had switched with an exact copy of herself from another dimension. This new Juvia was exactly like the old one, except for the fact that her bloodline was different, and new Juvia came from a world of darkness, where the sun had been blotted out generations ago. This is important for later.
With the switch complete, we continue with the campaign, accumilating multiple new levels and powers. Evenually, we come to find out that what we thought was the big bad, a vampire anti-paladin named Nightman, was actually the servant of an evil god, and Nightman's ultimate goal was to break a protective barrier around the world so that his master could invade, bringing unending darkness in his wake.
Due to Akatsuki voting to let an important ritual to break the barrier run it's course "just to see what happens", and the others being forced to follow his lead, the barrier was broken, and the world was plunged into darkness. Not long after, Juvia discovered that her father, Rixon, was actually allied with the darkness, and that it was the source of Original Juvia's shadow bloodline. Rixon took no part in the fighting, or in the ritual, but had long ago cracked the barrier, Allowing the dark god to spread his influence to followers in our world, and was promised protection for him and Nine-Tail Island as thanks by the dark god. Juvia was unsure of how to take this news, but she played nice with her father, not wanting to break their bond, and even used some magic dye to stain his clothes pink as a playful prank before teleporting away.
We decided, as a group, to go after Nightman first, naming him as the biggest threat to us that was also within our power to defeat. As we began making plans, and gained a new level, I had a sudden idea while looking through my newly-available spells to choose, as I had finally gained eighth-level spells. One in particular sparked an idea in me, and while I knew it wouldn't pay off for a long time, and several things had to go right in order for it to work, I was determined to see it through. And thus, I began my preparations.
My first step was to go to a jeweler as soon as I could, and I purchased a 50k gold diamond that took most of my funds to aquire. The DM and party had no idea why I needed such an expensive diamond, but I simply shrugged and told them "I need it for something later", and they soon forgot I even had it. My second step was to cast Legend Lore on Nightman, which granted me the last bit of information I needed for my plan. My third step was to purchase a specific magic item with my remaining gold, which gave me a significant boost to a specific skill that I needed for this to work. After that, all I had to do was wait, and keep suspicion off of me.
Three months passed out of game, and we reached level 18. Finally, we had tracked down Nightman, and we rushed in to confront him, only to be met with a terrifying sight. Just as we entered the room he was in, Nightman had just finished a ritual, and had brought an ancient red dragon back from the dead in a new, terrifying undead form. He then made an alliance with the newly-raised dragon, and mounted her as combat started, mirroring Akatsuki's style of fighting from Mizuki's back. Roll for initiative.
This was it. This was the fight I had spent three months planning and preparing for. Initiative was rolled, and I managed to get fairly high. I was second on the initiative order, right behind Akatsuki, who spent his turn bolstering the group's defenses with his abilities. My turn. I used Greater Teleport to teleport myself onto the dragon's neck, right in front of Nightman. My party was confused. As a sorcerer, Juvia was quite squishy, and tended to stay in the back as she peppered the enemies with Fireballs or Disintegrate rays. Getting into melee was not something she ever willingly did, let alone with a boss this powerful. I ignored their confusion, and described how Juvia uses her free action to take the 50k diamond from her robes, and kneels down before Nightman, offering him the gem.
"Nightman. I am Juvia, daughter of Rixon, head of the Nine-Tail Council. My father is allied with the darkness, and as his daughter, I swear my loyalty to you and your forces. I come from another dimension, a world where you had succeeded generations ago, and the world is shrowded in darkness. I miss that, and I want it again. Please, take this offering as a sign of my loyalty to you, and to the darkness."
The DM tells me to make a roll, either Diplomacy or Bluff, and to whisper the result to him. I was nervous. This one roll was what those three months had led up to. I choose my skill, and make my roll.
With all my modifiers and buffs, it came to a total of 68.
The DC had been set, and I prayed to the dice gods for this to work. The DM made his roll, and then described how Nightman gave Juvia a suspicious look for a moment, before reaching out and willingly accepting the diamond from her hand. As Nightman began to speak, I interrupted the DM, and with a sense of calm excitement, I say "As Nightman willingly accepts the diamond, and opens his mouth to talk, he suddenly freezes. His body dissolves into dust, and the dust is sucked into the diamond." I then show everyone the spell that had been cast on the diamond three months prior: Trap the Soul.
The way this spell works, is that it's an 8th level spell that traps a single, specific target's life force and material body inside of a diamond. The diamond had to have a monetary worth of 1000 gold per hit die of the targeted creature. I chose to go with a 50k gold diamond to be on the safe side. In addition, there were two ways that the spell could be triggered, both requiring the creature's true name, the bit of information I gleamed from the Legend Lore spell. The first way was to cast the spell on the spot, in which the target was afforded a Will save to try and resist. If they succeeded, the gem would shatter, and the spell would be ineffective.
I went with the second option, however. The second, more devious, way to trigger the spell was to inscribe both the creature's true name and the final word of the spell into the gemstone, and if the target willingly took the gemstone, they would be trapped inside the gem immediately, no save, no spell resistance.
And Nightman had rolled a 65, failing on his Insight check against my Bluff check.
As they finished reading the spell, and realized what I had done, there was a stunned silence that I broke by smirking and stating "That's why I needed the diamond."
We still had to fight the dragon, and it did end up escaping, but to this day, that is my proudest moment in DND: the time that I tricked an evil boss into trapping himself in a diamond forever.