Shadow Warrior

this in a way is not a very common style, but it is certainly very interesting because instead of dedicating yourself entirely to the sword, or training to be able to blend in with the shadows, increasing your stealth, this fighting style mixes very well both, thus making an impressive warrior.

Surprisee!

Starting at 3rd level, when you attack a surprised creature and the attack hits, that attack is an automatic critical.

Shadow Stab

At 3rd level, you can gain sneak attack against a target if both you and them are in darkness. This bypasses the normal rules of sneak attack. At 8th level, you can use this while both you and the target are in dim light.

Unbound Agility

Starting at 3rd level, you've learned to be quick to avoid protracted conflicts. Increase your movement speed by 10 feet while you are not wearing medium or heavy armor. In addition, you can take the disengage, run, and hide actions as bonus actions.

Extra Attack

Beginning at 7th level, you can attack twice, instead of once, whenever you take the Attack action on your turn.

The number of attacks increases to three when you reach 11th level in this class.

Uncanny Dodge

Starting at 9th level, you have learned to use your superior speed to dodge foe’s attacks. When an attacker you can see hits you with an attack and you aren't incapacitated or grappled, you may use your reaction to halve that attack's damage against you. If you use this feature against a Multiattack, the damage of every attack in the multiattack is halved.

Counter

Starting at 13th level, you've learned to exploit your opponent's moment off balance after a strike. When an opponent within 10 feet of you makes an attack and misses, you may immediately make an attack against your opponent as your reaction.

Dark Determination

Starting at 17th level, you have learned to always maintain your skill, especially in the direst of circumstances. When you are below 50% of your maximum hit points, you gain a +2 bonus to your AC and saving throws, and a +3 bonus to your attack and damage rolls.