Lyandra Sunstrider

Lyandra Sunstrider is an undead blood elf, a distant relative of the Sunstrider family and the latest wielder of Felo'melorn, which she retrieved from Icecrown Citadel before being killed and raised by the Scourge. She is encountered in the area that once housed the Crimson Hall within Icecrown by fire mages seeking to claim the legendary sword.

Biography
Lyandra is a distant relative of the deceased Anasterian Sunstrider, the last king of Quel'Thalas. Though she bore the Sunstrider name, in truth her branch of the family held no claim to the throne. After the betrayal of Kael'thas Sunstrider to the Burning Legion, Lyandra became obsessed with finding the royal elven runeblade Felo'melorn to claim it for her own and validate her claim to the Sunstrider throne, despite Aethas Sunreaver telling her that it was a fool's errand. By the year 32 ADP, Aethas had apparently not heard from Lyandra for several years.

Lyandra eventually discovered that after Felo'melorn was lost by Kael'thas, it had been taken to Icecrown Citadel and that it resided there still. She made her way through the empty, labyrinthine halls of the citadel until she found the blade mounted upon a dais at the end of a dismal passage. Just as she reached out to claim the sword, however, the door slammed shut behind her, trapping her within. Before long, Lyandra was raised as an undead minion of the Lich King, who entrusted the blade to her to aid in battle against the Burning Legion.

When the Legion returned to Azeroth, Aethas Sunreaver decided to begin his own search for the location of the blade. He saw a vision of Lyandra with Felo'melorn in hand, surrounded by land covered in ice and with Icecrown Citadel looming behind her. Thus, Aethas contacted Archmage Modera in the hopes that assisting in recovering the blade would convince the Council of Six to allow him re-entry into Dalaran. Modera, in turn, contacted a mage adventurer who thereafter journeyed into Icecrown Citadel, fighting their way past the minions of the Scourge and finally confronting and defeating Lyandra with Aethas' aid. After Lyandra's death, Aethas commented that "An inglorious stain upon the Sunstrider name has been cleansed."

Objective of

 * Lyandra needs to be killed for the fourth and penultimate stage of The Frozen Flame.

Speculation

 * Though she was said to have been killed by the Lich King, it's unknown if it was Arthas or by the Scourge under Bolvar, as all that is known is she had been missing for years and had been killed and raised as a member of the Scourge. The ambiguity in at what time she died leaves it up to question, as it could have been at any time between Kael'thas' betrayal of joining the Burning Legion, up to even as close as a few days prior to the meeting between the mage, Aethas and Modera.
 * It is not even known if the betrayal by Kael'thas refers to prior to his defeat in Outland when it was learned he'd switched sides, or his subsequent attack on Silvermoon and Quel'Danas. All that is known is that she disappeared searching for the blade at some point over the years since that point.
 * Bolvar, as the Lich King, says to mages that enter the Citadel in search of the blade that he will not protect them, and that should they fail they will be raised as members of the Scourge just as she had, yet this could imply either he chose to raise her as a minion and that she had died after the war in Northrend, or that she already was a member of the Scourge by the time he took up the mantle.
 * The easiest way to interpret Lyandra's distant relation to Dath'Remar is that she is directly descended from relatives of him, say a paternal uncle or cousin, for example.
 * She may be a blood mage, as the Crown of Endless Knowledge / Tourmaline Crown she is wearing somewhat resembles Verdant Spheres.