Tactician

A fighter whose greatest strength is that they are almost always one step ahead of their opponents, or at the very least they have a great exit strategy 

Bonus Proficiency

When you choose this archetype at 3rd level, you gain proficiency in three of the following skills of your choice: Arcana, History, Investigation, Nature, or Religion. Additionally, you learn three languages of your choice.

That Doesn't Make Sense

You have advantage on saving throws against Charm Spells/Effects or Spells/Effects that do Psychic Damage.

Know How

When wielding a weapon, with the finesse, light, versatile or ranged descriptor you may use your intelligence, instead of your strength, or your dexterity (whichever is applicable), when making your melee attack and calculating damage with that weapon. When you make an attack using your intelligence your weapon attacks score a critical hit on a roll of 19 or 20.

Look Out!

At 7th level, you learn to guide your comrades out of harms way. If you or a creature you can see within 30 feet of you is hit by an attack, add your intelligence modifier to their AC until the end of your next turn. 

You may use this feature a number of times equal to your Intelligence modifier (minimum of once), and you regain all expended uses of it when you finish a long rest.

I Know You...

Starting at 10th level, as a Bonus Action you may make an appropriate intelligence ability check to determine the vulnerabilities or common fighting tactics of your enemy. You must use a bonus action for each inquiry (vulnerabilities or fighting tactics) and can only do each check once per encounter. Based on your extensive studies and knowledge this check is DC 15.

No You Dont!

At 15th level, you become a master of locking down your enemies. Creatures provoke an opportunity attack from you when they move 5 feet or more while within your reach, and if you hit a creature with an opportunity attack, the target’s speed is reduced to 0 until the end of the current turn.

I Know Everything

Starting at 18th level, your extensive studies have now completely unlocked your mind. You have expertise in all INT ability checks.  When using your I Know You... ability you can make both checks with the same bonus action. You also have become so good at predicting your enemies that you can now, as a reaction, add your Intelligence modifier to the saving throw of anyone you can see within 30 feet. You may use this reaction after the save is rolled but before you know the outcome of the save. You may use this reaction a number of times equal to your Intelligence modifier (minimum 1) per long rest.