An Intelligent Swashbuckler. This duelist rogue is, not surprisingly, closely based on the swashbuckler rogue released in the Waterborne Adventures Unearthed Arcana and later in the Sword Coast Adventurer’s Guide. The primary difference is that it is based around using intelligence, rather than charisma, to support its combat and social abilities.
You are an expert at the art of parry and riposte, at reading your opponent and exploiting their weaknesses to maximize your impact. While other combatants might fight in heavy armor and use brute force, when you fight you are constantly on the move.
Duelists excel in single combat, but can also work well with others by taking advantage of the distractions they provide to your enemies.
Starting at 3rd level, you are a continuous blur of motion in battle as you dart in, attack, and slip away to safety. During your turn, if you make a melee attack against a creature, that creature cannot make opportunity attacks against you for the rest of your turn.
Starting at 3rd level, your ability to quickly analyze your surroundings allows you to determine how others around you will behave and react to it quickly. You add your Intelligence modifier to your initiative rolls.
In addition, you can use Sneak Attack with a melee attack even without advantage, when there is no creature other than your target within 5 feet of you. All other prerequisites of Sneak Attack still apply.
At 9th level, your observation of your enemies’ moves allows you to react instantly to their preoccupation. As an action, you can make an Intelligence (Investigation) check contested by a creature’s Charisma (Deception) check.
If you succeed on the check and the creature is hostile to you, if it makes an attack against a creature other than you or moves at least 1 foot away from you, you may make an Opportunity Attack against it, even if it took the Disengage action. This effect lasts for 1 minute or until you and the target are more than 60 feet apart.
If you succeed on the check and the creature isn’t hostile to you, your ability to read them is increased for 1 minute. During this time, you gain advantage on any Wisdom (Insight) checks on them, such as to determine their motives or whether they are lying.
Starting at 13th level, You complete difficult maneuvers with practiced ease. Starting at 13th level, you can use a bonus action to gain advantage on the next Dexterity (Acrobatics) or Strength (Athletics) check you make on that turn.
Beginning at 17th level, your mastery of the blade lets you turn your opponents’ errors to your advantage. If an opponent misses you with a melee attack, you may make an opportunity attack against them with advantage. Once you use this feature, you may not use it again until you finish a short or long rest.