Spirit Warrior

A dwarf walks into a orc camp entirely alone carrying his trusty axe. As the orcs draw there weapons and mock the dwarf for his stupidity walking into there fort. As they all finally surround him they see the sky erupt with ghostly looking dwarfs all screaming and crying. As terror grips the barbaric tyrants the dwarf yells that he has come to avenge his clan.

A wood elf is knocked off her horse by a raging troll just as she hits the ground a ghostly figure of another female wood elf helps her to her feet. Both now wielding scimitars the wood elf ad her fallen sister rush the troll. 

A hobgoblin stands in the middle of a fork in the road with chimera prints leading to the left. As he continues to follow it a specter of his father appears reminding him of the weak spots in a chimera's hide. As he arrives to its den he unsheathes his fallen father's blade and says he will carry there name with honor and pride. 

Spirit Warriors are fighters with ties to the spirit realm whether that is from ancestors or fallen comrades. They seek to honor those who have passed in combat before them and seek out to avenge or please the spirits that guide them. They are outcasts of normal society due to their ability to harness powers from spirits and seeming only partially alive themselves. 

Commune with the Past

Upon choosing this subclass you can call forth the spirit/s of past warriors you have some sort of connection with. Whenever you make an ability check or saving throw as a reaction you can gain advantage on it due to the help and guidance of the summoned spirits. You can do this an amount of times a day equal to your WIS modifier. 

Vengeful Dead

At level three the spirits that guide you also enhance your martial ability. Once per turn as a bonus action you can attack and add 1d6 + your WIS modifier as necrotic damage to that attacks damage. 

Blessing of the Forefathers

At 7th level whenever you finish a long rest you gain 2 a Spirit Dice, this spirit die is a d4 that can be added to any d20 roll and to your vengeful dead (attack or damage roll). These only last for 24 hours and you gain an additional die at levels 10, 15, and 18. At level 15 these dice become a d6 and then a d8 at level 18. 

Haunting Strike

Upon reaching level 10 your Vengeful Dead ability you can make your spirits haunt your enemy. After attacking as a bonus action using Vengeful Dead your target must succeed a CON save of 10 + your proficiency bonus + your WIS modifier on a fail they become vulnerable to necrotic damage and have disadvantage on saving throws till the end of your next turn.

Spiritual Guidance

When you reach level 15 your spirits lend you there knowledge and expertise. Once per short rest while making an ability or tool check you are not proficient in you can add your proficiency bonus only for this check. If you already have proficiency then you gain expertise for this one check. 

Rage Beyond the Grave

At level 18 as an action on your turn you can summon a ghostly warrior to aid you in battle. It's AC equals 12+ your WIS modifier, it's hitpoints equal your WIS score plus your proficiency bonus, and it can make 3 attacks a turn either a melee attack dealing 1d8+ your WIS modifier in necrotic damage or a ranged attack dealing 1d6+ your WIS modifier in necrotic damage. Its attack roll bonus is your proficiency bonus + WIS modifier. This spirit comes in intuitive order right after you and can also spend it's reaction to divert any attack from you to it while within 10 feet of you. When needing to make a saving throw its save bonuses are the same as yours.