Frostmourne

Frostmourne Artifact Requires Attunement
Unique
Heavy, Two-Handed Greatsword +3 Hit/Damage Crit 19-20 2d6 Slashing +3d8 Cold Passive: You have resistance to cold, shadow, and necrotic damage and can't be Charmed or Frightened. You are aware of the presence of Tiny or larger creatures within 60 feet of you that aren't constructs or undead. "Whomsoever takes up this blade shall wield power eternal. Just as the blade rends flesh, so must power scar the spirit."

Frostmourne was the mourneblade magnum opus of the tothrezim Vilateth, which had been made on commission for the Burning Legion. A fearsome, rune-inscribed two-handed greatsword it possessed the power to consume and imprison the souls of its victims and could resurrect the fallen into powerful undead.

History

Frostmourne was crafted by the tothrezim Vilateth as a commission for Kil'Jaeden the Deceiver, and was considered to be her magnum opus. The blade was first given to Arthak Saurfang so that he could wield it in the conquest of Azeroth, and when he took up the blade, the first soul it claimed was his cousin, Dranosh. When the Dark Portal was being opened to invade Azeroth, it was intended for Arthak to slay the shaman Ner'zhul, as he was deemed to be a dangerous wildcard by the Legion. However, when Ner'zhul was run through by the blade, he was able to sever the attunement to Arthak, and fell through the unstable portal with Forstmourne.

The instability of the portal thrust the blade into Thas'alah, the heart tree of the Eversong Woods, where its evil presence twisted and corrupted the land around it, turning it into a dead, frozen wasteland. Eager to retrieve the blade, the dreadlord Mal'Ganis, as well as several representatives of the Horde and Legion (including Aracyra, Garrosh Hellscream, and Jorin Deadeye), were sent to reclaim it, however Kael'thas Sunstrider and several of his comrades also sought to claim the blade in order to keep it out of Legion hands.

Under the frozen boughs of Thas'alah, a fight erupted, and Lana'thel Dawnseeker claimed the blade for her own, recognizing that its power was the only thing that could ensure she and her companions would not fall victim to Mal'Ganis and his machinations. The dreadlord was slain before he could completely consume the soul of her king, and with the power of Frostmourne she resurrected Kael'thas into the first san'layn, and with him, many other elves that fell in the land that would come be known as Deatholme.

Lana'thel continued to wield Frostmourne in the following attack on Quel'danas and the Sunwell Plateu as the elven forces sought to close the portal that was ushering demons into their world. Lana'thel and her Blood Knights attempted to draw forces away from the Plateu by attacking the orcish village of Gramgun'kur. In the conflict, Lana'thel was slain by the combined efforts of Azgadaan and Nyxxa, and her body was reclaimed by her people.

Frostmourne sought to consume Lana'thel's soul, but she fought back, forcing her will upon the blade and becoming its true master. Or perhaps one with it. In either sense, Lana'thel returned, with the runed blade at her side.

A blade that she further used to gain the favor of the goddess Helya and a tribe of vrykul on Northrend, as they viewed her as an avatar of the goddess of death. Through her dealings with Helya, she was gifted with the ability to use the blade to resurrect fallen vrykul into the renowned val'kyr.

Properties

When someone takes up the blade, they must be willing to sacrifice anything for power and strength. Attuning to the blade is instantaneous, but costly. When someone attunes to the blade, it immediately slays the creature whom the wielder cares deepest about within 100 miles, devouring their soul. Once a creature has attuned to this blade in such a way, the blade demands no further sacrifice if they must attune to it again.

You gain a +3 bonus to attack and damage rolls made with this magic weapon. The sword deals an extra 3d8 cold damage to any creature it hits, and it scores a critical hit on a roll of 19 or 20.
Chill of the Grave. While you are attuned to Frostmourne, you have resistance to cold, shadow, and necrotic damage. Additionally, while the sword is on your person, you can use an Action to cast one of the following spells (save DC 18) from it: animate dead, death coil, create undead, frost aura, unholy aura. Once you use the sword to cast a spell, you can't cast that spell again from it until the next dawn.
Devour Soul. Whenever you use it to reduce a creature to 0 hit points, the sword slays the creature and devours its soul, unless it has no soul, like most constructs, undead, or oozes. A creature whose soul has been devoured by Frostmourne can be restored to life only by a wish spell. The sword also immediately slays any creatures of challenge rating 0, as well as all plants that aren't creatures, when within 10 feet of the blade. When it devours a soul, Frostmourne grants you temporary hit points equal to the slain creature's hit point maximum. These hit points fade after 24 hours. As long as these temporary hit points last and you keep Frostmourne in hand, you have Advantage on attack rolls, saving throws, and ability checks.
Soul Hunter. While you hold the weapon, you are aware of the presence of Tiny or larger creatures within 60 feet of you that aren't constructs or undead. You also can't be Charmed or Frightened.
Sentience. Frostmourne is a semi-sentient neutral evil weapon with an Intelligence of 17, a Wisdom of 16, and a Charisma of 20. It has hearing and darkvision out to a range of 120 feet. The weapon can speak, read, and understand any language known by the souls it has consumed, including Orcish, Common, and Eredun. It can communicate with its wielder telepathically. Its voice is deep, raspy, and echoing. While you are attuned to it, Frostmourne also understands every language you know.
Personality. Frostmourne's consciousness is an amalgamation of the souls it has devoured, tempered by the cold pseudo-consciousness of the blade itself. Previously, the dark shaman, Ner'zhul, was the most powerful soul trapped within the blade. Until it was claimed by Lana'thel, he had imposed his will upon the blade, taking its power for himself.

Wielders