Diplomat

Any silver-tongued fool can be made ambassador to a peaceful land, but a wise ruler knows the value of a diplomat who can survive dangerous journeys and hostile courts. You were trained at the bardic College of Eloquence, learning to wield oratory with the same deftness as your blade. Your knowledge of courtly fashion, culture, and the fine arts allows you to navigate the aristocracy's complex web of parties, gifts, and favors.

Diplomats in a Dungeon

Playing the Diplomat is an obvious choice for an intrigue-focused campaign, but this subclass can be useful in dungeon exploration and combat as well. To begin with, don't forget you're a rogue - stealth and Sneak Attack are still your bread and butter. On the other hand, note that the subclass does not give you proficiency in any Charisma skill - whether you're an expert in persuasion is up to you.

You don't have many spell slots, but the buffs and healing spells on the Bard spell list make your Rogue into a viable support class, and if you have a healing potion to spend you can get the most out of your few healing slots while making the party fearless. if you have a high Charisma, you can use enchantments for crowd control. If you need to sneak away but lack concealment, try illusions.

Using your Ambassador features, you'll find that many dungeons contain intelligent creatures that just aren't all that motivated to fight you - they might prefer to play dice and gamble on letting you pass by. Just saying "take me to your leader" to a dungeon denizen can put the Diplomat in an advantageous position. 

At 9th level you become an expert at bribing guards and turning enemy mercenaries into employees. At 13th level, a diplomat played well will never be surprised by traps or ambushes, because you usually know where to find someone who can tell you all about the dungeon, and it soon becomes filled with your spies.

Bonus Proficiencies

You gain proficiency in one set of artisan's tools. You also gain proficiency in one musical instrument, one gaming set, and one language of your choice. 

Ambassador

You can add double your proficiency bonus to Intelligence or Wisdom ability checks made to recall or interpret information about government, court culture, or other matters of state. 

Dice Diplomacy

Games provide the diplomat with a peaceful outlet for bitter rivalries, an excuse for discussions that might otherwise be avoided, and an opportunity to learn a player's strengths and weaknesses. You add 1d4 to Wisdom and Charisma ability checks you make while playing a game with the target of the check, or to convince them to play with you.

Diplomatic Contacts

Hobbies are a great way to meet new people. When you have downtime, you can gain a contact* who shares any of your proficiencies in artisan's tools, gaming sets, or musical instruments. Once you've used this feature, you can't use it again for seven days. 

*See Xanathar's Guide to Everything, under Carousing.

Soothing Ritual

You learn to perform a ceremony that calms the nerves and spiritually bolsters its participants. The casting time is 10 minutes. As a material component, the ritual consumes a Potion of Healing.

Choose up to six creatures. Each creature regains hit points equal to your Charisma modifier, minimum 1. For 1 hour, each target receives the maximum number of hit points possible from any healing. In addition, each target has advantage on saving throws against being charmed or frightened.

Spellcasting

When you reach 3rd level, you gain the ability to cast spells.

Cantrips

You learn three cantrips: message and two other cantrips of your choice from the bard spell list. You learn another bard cantrip of your choice at 10th level.

Spell Slots

The Diplomat Spellcasting table shows how many spell slots you have to cast your bard spells of 1st level and higher. To cast one of these spells, you must expend a slot of the spell’s level or higher. You regain all expended spell slots when you finish a long rest.

For example, if you know the 1st-level spell charm person and have a 1st-level and a 2nd-level spell slot available, you can cast charm person using either slot.

Spells Known of 1st-Level and Higher

You know three 1st-level bard spells of your choice from the bard spell list. The Spells Known column of the Diplomat Spellcasting table shows when you learn more bard spells of 1st level or higher. Each of these spells must be of a level for which you have spell slots. 

Diplomatic Secrets

When you learn spells, you can choose certain spells from other classes. These spells count as a bard spell for you: detect poison and disease, alter self, protection from energy, and aura of purity

Whenever you gain a level in this class, you can replace one of the bard spells you know with another spell of your choice from the bard spell list. The new spell must be of a level for which you have spell slots, and you must be replacing a spell you chose.

Spellcasting Ability

Charisma is your spellcasting ability for your bard spells. You use your Charisma whenever a spell refers to your spellcasting ability. In addition, you use your Charisma modifier when setting the saving throw DC for a bard spell you cast and when making an attack roll with one.

Spell save DC = 8 + your proficiency bonus + your charisma modifier

Spell attack modifier = your proficiency bonus + your charisma modifier

Spellcasting Focus

You can use a musical instrument (see the Tools section) as a spellcasting focus for your bard spells.

Diplomat Spellcasting

Lord of Gifts

You have advantage on Wisdom (Insight) checks to understand what gifts a creature might prefer. The gift may be an object, favor, title, invitation, or some other form of honor. 

When a creature accepts a gift from you and is impressed by it, you can choose one of the following benefits. The gift must be given honestly - the magic of gifts doesn't work if you deceive a creature into accepting a gift of little value, or if you plan to take back what was given. Once you use either benefit, you can’t use it again until you finish a short or long rest.

Overwhelming Appreciation. The creature is charmed by you for the next 8 hours or until you or your allies attack it, damage it, or force it to make a saving throw. The charmed creature is friendly to you.

Obligatory Reciprocation. The creature is compelled to provide you with a gift that they believe to be of equal or greater value. If the creature is able to provide you with a gift but does not do so within 1 minute, it must succeed on a Wisdom saving throw against your spell save DC or take 1d4 psychic damage. Until it reciprocates, the creature takes 1d4 psychic damage after regaining hit points at the end of each long rest. You can end this compulsion early by using an action to dismiss it. A Remove Curse, Greater Restoration, or Wish spell also ends it. A medicine check would suggest the psychic pain is caused by guilt, but a creature skilled in arcana may realize the compulsion is magical. 

Bonus Proficiencies

You gain proficiency in one musical instrument, one gaming set, and one language of your choice. 

Court Spider

By 13th level, you have become a master of courtly intrigue. When you make a Charisma ability check to scheme, you can choose to treat the d20 roll as a 20. You can do so after the roll but before any effects of the roll occur. Ability checks affected by this feature include:

• Carousing and establishing contacts.
• Hiring and motivating hirelings as spies.
• Gathering news and rumors.
• Spreading rumors, and preventing rumors from being traced back to you.
• Altering another creature's reputation.

Once you use this feature, you can’t use it again until you finish a short or long rest. When you use this feature to perform downtime activities, you cannot do so again until you spend one week in relaxation.

Ambassador to the Gods

When you reach 17th level, powerful entities owe you favors, which you can call upon in the form of spells. When you gain this feature, choose one spell from each of the following lists.

Choose one: Contact Other Plane, Dream, Rary's Telepathic Bond, or Teleportation Circle.

Choose one: Globe of Invulnerability, or Heroes' Feast.

Choose one: Magnificent Mansion, Plane Shift, or Teleport.

You can cast each of the chosen spells without the use of a spell slot. You regain the use each spell after 7 days.