Lanal'thel by Edgy.veggie

Lana'thel was a survivor of the Scourge invasion of Quel'Thalas, led by Arthas. In the aftermath she discovered the fabled blade, Quel'delar, The Sister Blade: A prismatic sword crafted by the Night Elves, and Dragonflight to oppose any threat to the races of Azeroth. With a seething revenge, and newfound power, her along with the remaining Blood Elves were led to Northrend by Kael'thas Sunstrider, and the Illidari forces; united under the common goal of stopping The Lich King, with the purpose to rekindle the Sin'dorei's former glory.

After Illidan's defeat, Kael'thas, and Lady Vashj were forced to retreat to Outland, and abandon their forces. Lana'thel was one of the survivors, personally sought out by Arthas. She fought valiantly with Quel'delar, but Frostmourn's evil powers overwhelmed her. She eventually fell, but like many before her, was denied the peace of death. He chose Lana'thel to serve, mutating her into Blood-Queen of the San'layn: the slaughtered remaining elves, converted to Vampirism by Lana'thel herself; responsible for overseeing the Scourge's operations across Azeroth.

Tasked with overseeing the forces of Undeath, she, and her people resided in the Crimson Halls of Icecrown Citidel while the war over the frozen wastes raged on. Lana'thel was plagued by the betrayal of her people, and eternal servitude, driven to insanity by the possession of Quel'Delar, and memories of her former life. Consumed by fury, yet powerless against it she shattered Quel'delar casting it into the Frozen wastes. She was executed and laid to rest by the champions of light led by Tirion Fordring.