Hasteknight

UIVE CELERITER ET BENE MORI!" (LIVE) fast, and die well!) the battle cry of Haste Knight squadrons. When they strike, it's as if they come from nowhere. Streaking across the battlefield as blurs and leaving behind waves of shattered
carcasses. A small group of these warriors is all it takes to up heave clinched victories, and they does so in a blink of an eye. Haste Knights learn to unlock their body's full potential and push themselves well beyond a normal person's physical limits.

Blinding speed

At 3rd Level you gain the following abilities as a result of your blinding speed 
-You can use the Dash Action as a bonus action, on your turn. When using the dash action in this way you are invisible while you are moving until the end of your turn. At any point on your turn, if you stop moving, Attack or Cast a spell you become visible again. You can use this ability a number of times per long rest equal to your Proficiency Bonus. You regain all expended uses of this ability at the end of a short rest.

-Whenever you roll for initiative, you may add your Constitution modifier to the outcome of the roll.

-You don't take damage from falling 20 feet or less and you are proficient in Acrobatics 

-Your movement speed is increased by 10 feet as long as you are not wearing heavy armor.

Adrenal Surge

At 3rd Level You can briefly push your body past its physical limits. As a bonus action, if your not wearing heavy armor you can imitate the effect of the Haste spell on yourself. You are not required to use any components or maintain concentration when using this ability. When used in this way, the effect of the Haste spell lasts a number of rounds equal to your Constitution modifier.
You can use this ability a number of times equal to your Proficiency Bonus, and you regain all expended uses of this ability after completing a long rest. Furthermore, you regain one expended use of this ability, after completing a short rest.

Remarkable Reactions

Starting at 7th level, you can add double your proficiency mod in your Acrobatics skill checks, you have advantage on initiative rolls and In addition, you can't be surprised, except when incapacitated by something other than nonmagical sleep. You awaken if you are sleeping naturally when combat begins. 

Slippery Bastard

At 10th Level You can tap into your haste like abilities for brief instances, making it nearly impossible to contain you or catch you off-guard. You have advantage on ability checks and saving throws to prevent or end the grappled, prone, and restrained conditions.
Furthermore, if a creature imposes one of these conditions on you from an attack and there is no saving throw, you can make a skill check to prevent the condition. You choose to make either an Acrobatics or Athletics check, and if the skill check is equal to or higher than the damage the creature delt, you take the damage as you would normally but no additional effects
Occur.

Extreme Conditioning

At 15th Level Your body has become accustomed to the constant strain and demands you put on yourself. When you are subjected to an effect that allows you to make a Constitution or Dexterity saving throw to take only half damage, you instead take no damage at all if you succeed on the saving throw. Additionally you no longer suffer from the wave of lethargy that normally overcomes you when your Adrenal Surge feature ends.  

Untouchable

At 18th Level You have Unlimited uses of Adrenal Surge, Furthermore, while under the effect of Adrenal Surge, when you are targeted with an attack, you can attempt to dodge it. You can use your reaction to impose disadvantage against one attack roll of your choice.