Striker

A striker is a warrior who has honed his speed to an inhuman level. They use this speed to increase damage, become harder to hit, and to make flurries of blows with ease. 

Speed State

Starting at level 3, as a bonus action, you may enter a state of heightened speed. While in this state, your movement speed is increased by a number of feet to 10 plus 5 for every 5 levels of fighter and opportunity attacks against you are made with disadvantage. You may use this ability a number of times equal to your proficiency bonus per long rest and it lasts for a minute

Fast Reflexes

At 3rd level, you add your Dexterity modifier to your initiative rolls

Flurry of Slashes

Starting at 7th level, while you are in your Speed State you can make one melee light weapon attack as a bonus action. 

This increases to 2 attacks at 15th level.

The Best Offence and Defence is Speed

At 10th level, once per turn, you may add a +2 to one of your attack rolls or a +2 to your AC until the start of your next turn.

Constant Blur

Starting at 15th level, during your Speed State, as a reaction to an attack, you can impose disadvantage on it and all attacks made against you until the end of the next turn. 

You may use this reaction a number of times equal to your Dexterity modifier

The Thousand Piece Puzzle

At 18th level, your speed has increased to the point when you can expend your body's energy to make a massive amount of attacks. When you take the Attack you may replace it with a use of this feature. If you do, roll 2d8. You may make that many melee weapon attacks against one creature within your range. You then drop to 0 hit points and fall unconscious. If you are not stabilised in the next minute, you die and can’t be revived by any means except Wish or True Resurrection.

You regain a use of this ability after a long rest.