This massive darksteel greatsword is scarred and pitted by countless marks from previous battles, and the weighty blade, standing as tall as a person, is bifurcated into two rune-scriven edges, the inner sides of which are marked by conspicuous burn marks. At the center of its hilt, a baleful ruby is clasped tightly, shimmering with inert power. A detailed inspection of the weapon reveals it to be ancient beyond measure, yet strangely resilient to the passage of time.

The Blackburned Blade is a legendary greatsword with the following properties:

+2 Enchantment. The greatsword has +2 to its attack and damage rolls.

The greatsword has +2 to its attack and damage rolls. Burden of Steel. A creature that wields the weapon must have a Strength score of at least 19 or suffer disadvantage on attack rolls with the Blackburned Blade. Additionally, the weapon cannot be used to make attacks as a reaction or bonus action.

A creature that wields the weapon must have a Strength score of at least 19 or suffer disadvantage on attack rolls with the Blackburned Blade. Additionally, the weapon cannot be used to make attacks as a reaction or bonus action. Indestructible. The Blackburned Blade cannot be destroyed or damaged save by a Wish spell or by the act of a god.

A wielder that attunes to the sword additionally unlocks the following features:

Soulfire. A creature of at least CR 1/2 that is reduced to 0 hit points by the Blackburned Blade causes the sword to burst alive with fire as the creature's soul is lit aflame as kindling for the sword. For 1 minute afterwards, the Blackburned Blade deals an additional 4d6 fire damage with every strike.

A creature of at least CR 1/2 that is reduced to 0 hit points by the Blackburned Blade causes the sword to burst alive with fire as the creature's soul is lit aflame as kindling for the sword. For 1 minute afterwards, the Blackburned Blade deals an additional 4d6 fire damage with every strike. Kindling Flame. Every additional creature of at least CR 1/2 that is reduced to 0 hit points by the Blackburned Blade adds an additional 1d6 fire damage to the damage of Soulfire and renews the duration.

Every additional creature of at least CR 1/2 that is reduced to 0 hit points by the Blackburned Blade adds an additional 1d6 fire damage to the damage of Soulfire and renews the duration. Blazing Inferno. When the bonus damage provided by Kindling Flame reaches 4d6, the Blackburned Blade burns with uncontrollable intensity. At the end of each of its wielders turns, it deals 2d6 fire damage to all creatures within an aura of 5 ft. of it, including its wielder. For each additional 4d6 damage provided by Kindling Flame, the damage of the aura increases by 2d6 and its size increases by 5 ft.

When the bonus damage provided by Kindling Flame reaches 4d6, the Blackburned Blade burns with uncontrollable intensity. At the end of each of its wielders turns, it deals 2d6 fire damage to all creatures within an aura of 5 ft. of it, including its wielder. For each additional 4d6 damage provided by Kindling Flame, the damage of the aura increases by 2d6 and its size increases by 5 ft. Consuming Glory. When the bonus damage provided by Kindling Flame reaches 10d6, any creature that takes fire damage from the sword must succeed on a DC 15 Wisdom saving throw or be overcome by a primal fear of being consumed by the sword's inferno. A creature that fails their saving throw is frightened of the Blackburned Blade for 10 minutes. While frightened in this way, a creature has vulnerability to fire damage inflicted by the sword. The DC increases by 1 every time a creature succeeds on their saving throw.

When the bonus damage provided by Kindling Flame reaches 10d6, any creature that takes fire damage from the sword must succeed on a DC 15 Wisdom saving throw or be overcome by a primal fear of being consumed by the sword's inferno. A creature that fails their saving throw is frightened of the Blackburned Blade for 10 minutes. While frightened in this way, a creature has vulnerability to fire damage inflicted by the sword. The DC increases by 1 every time a creature succeeds on their saving throw. Torch of Forgotten Prophecy. When the bonus damage provided by Kindling Flame reaches 20d6, the blade becomes a howling whirlwind of fire as it consumes one application of Kindling Flame at the end of each of its wielder's turns until extinguished. During this time, the sword ignores resistance and immunity to fire damage.