Echonight

Echo: 

• Summoning: As a bonus action, you summon the Echo within 15 feet of you. It has 1 HP and an Armor Class of 14 + your proficiency bonus.
• Movement: You can mentally command the Echo to move up to 30 feet in any direction—even straight up or into the air—without using any of your own actions.
• Attacking: When you take the Attack action, you can choose to have any of your attacks originate from your Echo's space rather than your own
  
• Swapping: As a bonus action, you can magically swap places with your Echo at the cost of 15 feet of movement, no matter how far apart you are.
  
• Surviving: The Echo is immune to all conditions and cannot be targeted by spells that only affect creatures. If it takes any damage, it is destroyed, but you can simply summon it again.

Manifest Echo (Level 3)

• Create a magical echo of yourself using a Bonus Action.
• The echo can move 30 feet in any direction each turn, including straight up.
• If the echo is destroyed or too far away, you can simply create a new one with another Bonus Action.
• You can teleport and swap places with your echo by spending 15 feet of movement.
• This can help you bypass obstacles, difficult terrain, and possibly grapples (depending on your DM's ruling).
• The echo is technically an object, not a creature.
• You can attack, make opportunity attacks, and use many abilities from the echo's location instead of your own.

Unleash Incarnation (Level 3)

• When you take the Attack action, you can make one extra attack from your echo's position.
• Uses per long rest = your Constitution modifier (usually 3–5 times).

Echo Avatar (Level 7)

• You can send your echo up to 1,000 feet away.
• You can see and hear through it.

Shadow Martyr (Level 10)

• When a creature you can see is attacked, you can move your echo in front of the attack.
• The echo takes the hit instead.

Reclaim Potential (Level 15)

• Whenever your echo is destroyed, you can gain temporary hit points.
• Uses per day = your Constitution modifier.

Legion of One (Level 18)

• You can have two echoes active at the same time.
• You can summon both with one Bonus Action.
• You gain an extra use of Unleash Incarnation whenever you roll initiative and have none left.

Level 3: Manifest Echo

Manifest Echo 

• Create a magical echo of yourself using a Bonus Action.
• The echo can move 30 feet in any direction each turn, including straight up.
• If the echo is destroyed or too far away, you can simply create a new one with another Bonus Action.
• You can teleport and swap places with your echo by spending 15 feet of movement.
• This can help you bypass obstacles, difficult terrain, and possibly grapples (depending on your DM's ruling).
• The echo is technically an object, not a creature.
• You can attack, make opportunity attacks, and use many abilities from the echo's location instead of your own.

Level 3: Unleash Incarnation

Constitution Score	Constitution Modifier	Uses per Long Rest

10–11

+0

0

12–13

+1

1

14–15

+2

2

16–17

+3

3

18–19

+4

4

20–21

+5

5

 

Whenever you take the Attack action, you can make one additional melee attack from the echo's position. (So basically whenever I do any form of attack, I can use Unleash Incarnation to do another attack. Attack action also includes things like Action Surge). Also, the extra attack uses whatever weapon attack you're making, so you roll the normal damage dice for that weapon.

Shadow Martyr

 

• Action Cost: Reaction
• Uses: 1 use per Short Rest or Long Rest
• Requires an active Echo: Yes
• Range Limit: None

My Echo only dies if the attack hits 14 AC + Proficiency Bonus. If this get proc'd/the attack hits, it dies due to only having 1 hp. 
Magic or attacks that has "creature" and does not include "object" will not hit the Echo and this can only work with other creatures I can see (I am not included).