This session was designed as part of a campaign taking place in the Riverlands, with the players representing minor nobles from the Touvette region. For obvious reasons, NPC names and origins may need to be altered to fit into other games more seamlessly.
The PCs are invited to a masquarade ball whether as official dignitaries, local heroes, or under the patronage of another noble.
During the event, there is a contest to correctly guess the most guests identities, with a prize of a cloak of repute for highest accurate count.
Schedule
Upon arrival, PCs asked to hand over any weapons, spell components, or other potential sources of violence. They are then given a guest list, and directed to changing rooms to don their disguises. Following that, it is time to mingle. It is assumed that the PCs are working together and sharing information.
Each PC is given 2 "Rounds" to socialize, representing roughly 30 minutes of grabbing food, drinks, and conversation with fellow guests to try and determine identities. Following this is a formal dinner beginning with a short speech by the host thanking them all for making the journey. This should be followed by a final event and the chance to identify guests. For my game I used the magic maze encounter.
Guests
The PCs are given a copy of the guest list containing the following names and the DC to learn basic details about them:
Achille Parsall DC 15
Amai Das DC 25
Berzan Shimba DC 20
Budi Aldori DC 17
Damri Ambo DC 25
Ergen Kiddik DC 15
Erinin Thulgath DC 20
Kera Selald DC 25
Kostov Frinned DC 12
Kotem Roth DC 17
Lollia Aldori DC 17
Natasha Liacenza DC 15
Railek Jazmin DC 20
Savi Aldori DC 17
Uasnarnant Ber DC 15
Ushe Sorn DC 20
Vaernligg Bensi DC 15
Vilo Munri DC 25
Vitess Roth DC 17
This alphabetical list is also presumed to be the seating arrangement with the players slotted in appropriately; however, you may instead wish to ensure the PCs are seated adjectent to some of the NPCs they have not yet identified to make conversation easier.
Each player rolls a single society check to determine how much if anything they know about the various guests. Within my game, players had some instances of lower DCs or automatic successes on certain guests that represented close ties of theirs. A result of 18 would give you the very basic info regarding everyone In the DC12-17 range.
The guests are largely well-covered but it is assumed that PCs can determine their fellow guests' race and genders. However half-elves appear elven initially. The attending gnome at the party is automatically identified, assuming a PC has rolled high enough to know who Uasnarnant is.
Layout
This is the initial guest layout at the time the PCs arrive to the party. NPCs are presumed to move about the event, although their exact movements are not detailed here.
Entryway - Kostov Frinned, Ergen Kiddik, Vitess Roth
Dining Hall - The Aldori sisters, Kotem Roth, Natasha Liacenza
Ball Room - Kera Selald, Uasnarnant Ber, Vilo Munri
Living Room - Berzan Shimba, Railek Jazmin
Wine Room - Damri Ambo, Erinin Thulgath, Vaernligg Bensi
Card Room - Achille Parsall, Amai Das, Ushe Sorn
A simple game called Wizard's War is being played in the card room. A d20+mental stat modifiers is rolled to simulate luck plus a various abilities such as bluffing, watching for tells, counting cards, etc. Additionally a player asking to cheat may do a DC20 thievery check to add their dex modifier to their roll. Amai is doing so, however, her thievery checks are generally much higher than a PCs passive perception. She will of course lose some hands to avoid suspicion, especially if a PC starts actively watching for cheating.
Attendees
Several of the attendees are assumed to be easily identified as they are making poor or no attempt to hide their identify.
Kostov Frinned - Human male wizard(host of the evening)
Kostov stands in the entryway greeting guests as they arrive. His identify is not overly secret and it is presumed he can be identified readily based on his elderly more frail apparance or at a minimum right before dinner giving a small speech to the assembled nobility.
Achille Parsall - Human male from Liberthane/Galt
Achille has no interest in hiding his identity and has only come to this meeting to beg any of the local nobility to help raise money or troops on his behalf for an expedition to retake Galt. Not having found a receptive audience thus far, he will approach any PCs that appear militant or have a reputation for commanding troops. However, he does not have any money, at least on the scale needed for raising and paying an army.
Uasnarnant Ber - Gnome fishery owner from Mivon
Being the only gnome at the gathering makes his identity rather easy to deduce. He takes this good naturedly.
Ergen Kiddik - Human Male from Pitax. Fighting pit champion
Sticking out like a sore thumb, Ergen appears to be a goliath of a man. Looking rather uncomfortable in ill fitting formal attire, Ergen can be initially found attempting to make polite conversation with the events host. He has been paid to be here but would much rather be fighting or talking about fighting.
Lollia, Savi, Budi Aldori. Human Females from Pitax
These 3 sisters can be found in the dining hall arguing the finer points of swordplay and the various merits of rostland bravo style techniques, etc. It is immediately obvious that they are the Aldori sisters, however, it is also nearly impossible to tell the sisters apart visually. The most reliable method of identifying them is challenging them to a duel and attempting to listen in as they identify themselves to retrieve their weapons.
Traditionally, the duels are for small amounts of coin or strictly honor. The standard terms are a fight to first blood, however, other terms could potentially be agreed upon if a PC presses for it. The Aldori possess the confident finisher swashbuckler ability which gives them a significant edge in drawing first blood.
The remainder of the guests are potentially harder to identify.
Vaernligg Bensi - Half elf female from Mivon - Hound trainer
The easiest way to identify Vaernligg as a half elf is a DC 20 perception check to that one of her eyes lacks an iris. She of course knows this and makes an attempt to avoid eye contact while speaking to people. Alternatively if someone suspects her identify, she can be easily dragged into conversations regarding training animals or her hunting hounds.
Natasha Liacenza - Human female from Pitax. Vineyard owner
Initially in the dining room politely listening to the Aldori discussion of fencing, she'll largely opt out of the conversation, although when the wait staff asks for drink orders of the PCs should any PCs possess nobility, cooking, or a related lore to order a fine vintage she'll compliment them on their tasks. Particularly so if one of the PCs thinks to ask for one of her make.
Vitess/Kotem Roth married male/female Elves from Embeth Forest
Both Vitess and Kotem are wearing blue costumes and masks with a demonic apperance. This may be enough to determine that they are there together. Identifying them both as elves will make it even more obvious who this pair must be.
Berzan Shimba - Elf male from Embeth Forest. Minor noble
Railek Jazmin - Elf female from Pitax. Minor noble house
Berzan and Railek are courting each other, however neither of their familes approves of the match. They can be found together for most of the evening, generally out walking in the gardens or alone in a side room. If intruded upon they will claim they were just about to depart and head somewhere else private.
Vilo Munri - Human male from Pitax. Minorly popular bard
Vilo can be found in exclusively in the ball room listening to the music and occasionally dancing as the need comes up. During the band's break he can be seen arguing with the musicians and may even approach a PC that has been friendly with him to intercede on his behalf, as he wishes to join in playing with the band. He has brought a cello and has it stashed in his carriage for just such an occasion.
Ushe Sorn - Human male from Pitax. Captain of the Guard
Can be initially found playing cards with Amai and Achille, with the latter imploring him to join his crusade. Ushe lacks the troops or the interest for this endeavour and will politely attempt to redirect the conversation. His professional militant bearing and conversation with Achille are hints to his identity.
Damri Ambo - Human female from Mivon. Very wealthy widower
An elderly lady who has been widowed multiple times. Has no patience for these social events and gruffly rebutts any attempt at opening a conversation. It is rumored that she has murdered her three previous husbands.
Erinin Thulgath - Elf from Pitax. Family of alchemists/herbalists
The Thulgath family is currently rather down on their luck and near destitute. He has come here attempting to find Kera Selald and try selling her alchemical supplies. The problem is he does not know which guest she is. He might approach any female PCs and ask if they are Kera, or ask for assistance in discovering her identity. If any PCs are well known alchemists or from wealthy families, he may attempt to deal with them as well.
Amai Das - Human female from Gralton
Das is a very small noble house and Gralton is farther afield than most of the guests. As such this individual is a complete unknown among the guests. However, the individual attending is in fact not Amai at all, but a notorious thief that intercepted the invitation and is using it as cover to rob some of the expensive artwork and items from the house. Should the players sneak upstairs later in the evening, they may notice some conspicuously blank walls or shelves. When not missing, she can be found fleecing the nobles in the card room playing wizard's war.
Kera Selald - Human female from Pitax. Reclusive but powerful and influential noble in Pitax
Kera is generally not possible to identify save via process of elimination. Supposedly a powerful member of the nobility, Kera is a persona used by a succubus running a powerful criminal cartel. She is attending this ball with the apperance of an elderly human male. Will engage in polite conversation, but short of any PCs being notorious criminals will not engage further than surface level talks with anyone. Outside of a PCs performance, she is the likely winner of the guessing contest having identified everyone save mixing up two of the Aldori sisters.
Additional Notes
This is a great way to set up or introduce a group of NPCs/Factions or various plot threads for the future. If you want a more action packed event you could add things like an attack on the party, an assassination, a murder mystery, etc.