Weapon

Legendary Requires Attunement

Soul Destroyer, Mark of Destruction. Whenever this sword deals fire damage to a creature that possesses a soul, the target is marked with a dark, charcoal-like burn. This mark signifies the beginning of its soul’s deterioration. The mark naturally fades after 7 days if not reinforced by additional hits.
If a creature is reduced to 0 hit points by the sword’s fire damage, its soul is obliterated. Such a creature cannot be restored to true life by any means except by a Wish spell or comparable divine intervention (e.g., Miracle, powerful ritual magic).

Fire Tolerance Decrease.Whenever the Blade of Belial deals fire damage to a creature, it undermines the creature’s innate resistance to fire.
Fire-Immune creatures are treated as fire-resistant.
Fire-Resistant creatures are treated as having no resistance.
Creatures with no resistance are treated as vulnerable to fire for that attack.

Hellfire Unleashed.As a bonus action, the wielder can invoke the power of the infernal gems set in the blade. While active, the sword is sheathed in blazing hellfire, Every attack made with it deals an extra 2d6 fire damage.
The effect lasts until the wielder uses a bonus action to end it or until the sword is dropped or sheathed.

Hellfire Obliteration (1/Day). Once per day, as a bonus action, the wielder can channel the blade’s full infernal might, coating the weapon in a blazing inferno of Hellfire. The next attack that hits during that turn deals an extra 8d6 + 30 fire damage (rolled separately from the weapon’s normal damage, so a critical strike does not double the damage dice for this skill).
If this damage reduces a creature to 0 hit points, its body and any worn non-magical gear is instantly reduced to ashes, and its soul evaporated, like with the disintegration spell.