Soul Returner

Long ago, there was an order of knights who dealt with benign necromantic magic. They became the knights known as Soulmongers. However, the power to freely control the souls of their dead enemies or even allies quickly corrupted many Soulmongers. After the fall of the Soul Tyrant Marcoths the Soulless, one of the most powerful Soulmongers ever, the Soul Returners were formed. Dedicated to return the dead to the grave, they are the opposite of Soulmongers. When they aren't beating up every undead monster in their path, or any other threats to innocent civilian populations, they oversee funerals and other things of the like.

Ashes to Ashes

At 3rd level, you have the slight ability to manipulate death and undeath. Whenever a creature cast a necromancy spell with at a level equal to or less that 1/3 of your level, and are within 30ft of you, you can add or subtract, your choice, your CON modifier from the damage rolled. Note that only the caster has to be within 30ft of you, not the target.

Undead's Odor

At 3rd level, you also have the ability to sense the presence of undead that are near you. As an action, you enhance your sense to detect any undead within 60ft of you. This doesn't tell you the undead's identity. You can use this a number of time equal to your CON mod.

Inured from Death.

At 7th level, you become more resilient to the powers of the undead. You have resistance to necrotic damage, and undead have disadvantage on attack rolls against you. You also have advantage on STR, DEX, and CON saves against effects from undead or attacks that would deal necrotic damage.

Guardian of the Veil

At 10th level, you are now a guard of the veil of life and death, and you decide who can enter and leave. Whenever a creature within 60ft of you drops to 0 hit points, you can use your reaction to stabilize them. If there is a creature within 60ft of you who is unstable at 0 hp, you can use a bonus action to stabilize them. If there is a creature that is stable at 0 hp within 30ft of you, you can bring them to 1 hp. You can only bring creatures up to 1 hp a number of times equal to your CON mod.

Besides just being able to keep others from entering the veil, you can also force others closer to the veil. You have a pool of hp equal to 2*your level. When you hit a target with a weapon or unarmed attack, you can deal additional necrotic damage by subtracting up to 1/2 your level of hp from that pool, and adding that number to the damage.

Soul Prison

At 15th level, you have realized that some souls are too dangerous to be allowed to pass on. You have created a demiplane within yourself that you can send souls to. You can hold a number of souls equal to your level in this prison, and if your prison is full and you try to imprison a new soul, you have to let another soul pass on. To claim a soul, you must target a creature that has been reduced to 0 hit points, and if they died within the last round, their soul is absorbed into you. After a soul is absorbed, they can't be revived by any magic short of wish, unless your release the soul. This imprisonment can interrupt a Naga's regeneration and can stop a liches revival and other effects like those. If fall unconscious, the souls will try to escape. You must make a save against a DC equal to the number of prisoners. If you fail, 1d4+1 souls escape, determined randomly. These souls do not escape when you sleep. You can expend 1-5 souls to create a necrotic explosion. When you do so, choose 1-5 souls, and for each soul used, the radius for this attack increases by 10ft and the damage increases by 1d8. The attack has a base attack range and damage of 10ft and 2d8 necrotic damage. You have to expend at least one soul to use this attack. The souls you use on this then are released. You choose which targets you wish to affect with this attack, and the targets must make Con saves against the DC shown above, 8+Your Proficiency+Your Con Mod.

Graveyard God

You have become so dedicated to protecting the boundaries of life and death that you have learned almost all that there is to know about the workings of life and death. Your soul prison can now hold 2x the amount of souls, and you have immunity to necrotic damage. Your soul prison also has one of the following modifiers:

• Palace: Your soul prison is a opulent palace with gold-plated everything. The souls in your prison are kinder to you, and even grant you power. You gain a +2 to attack and damage rolls with all attacks.
• Dungeon: Your soul prison is a dark and terrible dungeon made to strip away the prisoner's fighting spirit. You have a +2 bonus to the con save required when the souls try to break loose. You soul prison's max capacity is also increased by 10.

 When you fall unconscious, you unleash a dooming aura on all enemy creatures within 30ft of you. Those creatures take 1d8 necrotic damage per turn, have a -2 to attack and damage rolls, and have their speed decreased by 10ft.