The Spirit Knight is the result of a spirit being bound to the mind of a Warrior. While the host controls their own actions, the spirit may communicate with them psychically, cast some spells, and temporarily assume a physical form if necessary. This symbiotic relationship between living and dead can be advantageous, but not without strain upon the host whose sanity is at risk. The partial possession of the Spirit Knight gives them access to Supernatural abilities, but maintaining sanity while sharing their mind can prove tricky. 

 

This sub class is based on the echo knight sub class

Summon Spirit

At 3rd level, you can use a bonus action to magically manifest a Spirit in an unoccupied space you can see within 15 feet of you. This spirit is a magical, translucent, gray image that lasts until it is destroyed, or until you dismiss it as a bonus action, or until you're incapacitated. Only one Spirit may be active at a time, and can only be active for 10 minutes. You may summon the Spirit a number of times equal to your Constitution modifier (minimum of once) per long rest. if out of uses of Summon Spirit, any spell cast now has a 50% chance to fail.

The Spirit has AC 12 + your proficiency bonus, 1 hit point, and immunity to all conditions. If it has to make a saving throw, it uses your saving throw bonus for the roll. If it has to make an ability check, it uses your ability/proficiency bonus. is the same size as you, and it occupies its space. On your turn, the Spirit to move up to 30 feet in any direction (no action required). If your spirit is ever more than 30 feet from you at the end of your turn, it is destroyed.

• When you take the Attack action on your turn, any attack you make with that action can originate from your space or the spirit's space. You make this choice for each attack. Since the Spirit is the source of its host's magic, spells and cantrips learned from the Spirit Knight subclass must be cast from the Spirit's space. The Spirit is not proficient with any weapons. any attacks made by the Spirit use your spell modifier.
• if an enemy that the Spirit can see within 5ft moves 5ft away from the Spirit, the Spirit may make an attack of opportunity using your reaction.
• the Spirit is treated as a creature.
• You may allow a Spirit to cast a spell or attack as your bonus action. You can use this feature a number of times equal to your Constitution modifier (a minimum of once). You regain all expended uses when you finish a long rest.

Second opinion

While having a second voice in your head means you always have a second opinion, it also means your mind is more vulnerable to attack. Starting at 3rd level

• advantage on intelligence ability checks 
• vulnerability to psychic damage

Spellcasting

As a result of possession, your spirit can use your body to channel spellcasting. 

• Grants access to Warlock spell list, either Tasha's Hideous Laughter or Dissonate Whispers, and Thaumaturgy.

Spirit Bond

At the 7th level, your spirit's connection has grown, and so has its power, but at a cost.

• Your spirit now may maintain its form for up to an hour and has a max range of 150ft. 
• Your spirit can communicate with you telepathically while in its physical form.

Frighting Appearance

At level 10, the Spirit has truly mastered making an appearance. Upon summoning, all enemy creatures who are able to see the Spirits summoning must make a wisdom save against your spell DC, upon failure the target creatures are frightened until the start of your next turn.

Borrowed Life

At 15th level, your spirit is now able to 'borrow' some of your health to sustain itself. 

• Your spirit now has a max hit point score equal to your own
• any damage done to your spirit is reflected to you
• any damage done to you is reflected to your spirit. 
• Your spirits AC is increased to 16+ your proficiency bonus. 

Persistant Spirit

at 18th level, Your spirit may teleport up to 30ft, 3 times per summon. You may also swap places of with the spirit as a bonus action. If, when rolling initiative, you have no more uses of summon spirit, you gain 1 more.