Soul Knight (5e Creature)
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Medium humanoid (tiefling), lawful evil
Skills Athletics +8, Deception +6, Stealth +6
Devil's Sight. Magical darkness does not impede the soul knight's darkvision.
Fiery Weapons. The soul knight's weapon attacks are magical. When it hits with any weapon, the weapon deals an extra 9 (2d8) fire damage (included in the weapon attacks below).
Ferocious Surge (Recharges after a Short or Long Rest). When this creature hits with a weapon attack that isn't a critical hit, it can turn that hit into a critical hit.
Infernal Tactics. This creature has a keen eye for seizing tactical advantage. Immediately after rolling initiative, it can choose itself and up to four other allies it can see if it isn't incapacitated. It can swap the initiative results of the chosen creatures among them.
Innate Spellcasting. The soul knight's innate spellcasting ability is Charisma (spell save DC 14). It can innately cast the following spells, requiring no material components:
+1 Longsword. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 10 (1d10 + 5) slashing damage plus 9 (2d8) fire damage. When the soul knight reduces a living creature to 0 hit points using this sword, the creature is instantly slain as it's soul is taken and sent to the Nine Hells. The creature cannot be restored to life by any means short of divine intervention. After slaying a creature in this way, the soul knight regains 50 hit points, recharges its Ferocious Surge, and can teleport up to 120 feet. The longsword disintegrates when the soul knight dies.
Javelin. Melee or Ranged Weapon Attack: +7 to hit, range 30/120ft. one target. Hit: 7 (1d6 + 4) piercing damage, plus 9 (2d8) fire damage.
Some people want power, but they aren't willing to give up their own soul. Thus, soul knights use others' souls to gain power. These knights use the power of arch devils to slay. Whenever they kill someone, they are rewarded with a sudden burst of power. When they kill someone with their swords, the weapon draws the soul from their prey's body and sells it to the devil they made a contract with. The knights must slay powerful warriors or mages to keep up their power, because the souls of pure and good heroes are what devils use to advance in ranks. A farmer whose soul turns into a weak lemure isn't going to help anyone, but a mighty king turned ice devil is going to.