Sindragosa

Sindragosa, formerly the prime consort of Malygos up until her death during the War of the Ancients, was a mighty frost wyrm raised by the Lich King himself to serve as the queen of the Frostbrood. She was ultimately defeated by a group of adventurers in Icecrown Citadel.

Death
Long before the Great Sundering, Sindragosa was the beloved consort of Malygos, Aspect of the blue dragonflight and guardian of all arcane magic. During the War of the Ancients, Neltharion the Earth Warder, Aspect of the black flight, convinced his dragon brethren to empower a powerful artifact called the Dragon Soul, claiming that it would thwart the impeding invasion of the demonic Burning Legion. However, Neltharion betrayed his dragon allies during the Legion's assault, provoking an apocalyptic battle in the skies over the Well of Eternity. Malygos and Sindragosa joined the blue dragons in surrounding the Earth Warder and charged the black dragon. However, Neltharion used the might of the the Dragon Soul to strike out, decimating nearly all of the blue dragonflight. The blast mortally wounded Sindragosa and hurled her far across the land, deep into the frozen north.

Blinded and near death, Sindragosa sought desperately to reach the Dragonblight — the place where dragons instinctively travel to die. Weakened and no longer able to fly, Sindragosa plummeted to the cold earth in the peaks of Icecrown. The blue dragon gathered what remained of her energy and called out to Malygos for aid. Her only answer was the howling arctic wind as she struggled on, but the distance was far too great; agonizingly, she realized that her spirit would not find rest within the Dragonblight. Her life continued to fade away as her sanity deteriorated. In the midst of her delirium, Sindragosa's final thoughts turned to bitterness and hatred: hatred against the Legion, hatred against Neltharion, hatred even against Malygos. But most of all, hatred against the world of mortals. And in her dying moments, Sindragosa vowed revenge.

Wrath of the Lich King


Thousands of years later, Arthas Menethil, the Lich King, awoke from his long dormancy and journeyed to Sindragosa's Fall, where he raised Sindragosa into undeath as a mighty skeletal frost wyrm and ordered her to lead the Frostbrood into war. The Lich King tore the spirits of Sindragosa's lost whelps into undeath in front of her skeletal form as a final affront to the great dragon. Arthas was known to use Sindragosa as a mount.

Sindragosa briefly appears in the Pit of Saron after the defeat of Scourgelord Tyrannus. While the leader of the army of liberated slaves (Martin Victus for the Alliance, Gorkun Ironskull for the Horde) commends the adventurers for their bravery, Sindragosa rises up from the pit behind them and unleashes her fury, killing the leader and their army. The adventurers are pulled back to the entrance tunnel by Jaina Proudmoore or Sylvanas Windrunner at the last second, saving them from a grisly death.

Sindragosa later retreated to her lair in the Frostwing Halls of Icecrown Citadel, where she continued to strengthen her brood with the help of Ymirheim's vrykul. After Valithria Dreamwalker was rescued by adventurers, she gave the heroes verdant life crystals to use during their battle with Sindragosa. Valithria instructed the champions to battle the Frost Queen until she was weakened, and then use the crystals to coax out the essence that was dormant within her. Similarly, Darion Mograine instructed would-be wielders of Shadowmourne to grant Shadow's Edge its final infusion of power by subjecting themselves to four of Sindragosa's frozen breath attacks before ultimately destroying her. Sindragosa was finally defeated by adventurers in Icecrown Citadel, and her crystalline essence was brought to Kalecgos at Wyrmrest Temple. Upon receiving the essence, Kalec stated "So much suffering, so much needless destruction. These have not been kind times for my brothers and sisters. But thanks to your efforts, brave adventurers, this darkened yet still noble soul may find peace at last. Rest now, Sindragosa. You are home...."

Trivia

 * Sindragosa's name is likely a portmanteau of the words "sin" and "dragon", along with the traditional female blue dragon suffix "-gosa".
 * Sindragosa was featured on the Wrath of the Lich King login screen first introduced in patch 3.0.2. Many players came to love and/or hate her ferocious roar.
 * Sindragosa was one of the first two Icecrown Citadel bosses to be announced, the other being the Lich King himself.
 * Unused storyboards and animations for the Wrath of the Lich King opening cinematic indicate that at some point, the cinematic was to depict the battle between the dragonflights over the Well of Eternity and Sindragosa's subsequent death.
 * Like Lord Marrowgar, Sindragosa's model was changed in China due to Chinese law prohibiting the showing of bones in video games. Therefore, she instead uses a slightly modified blue dragon model.
 * Breath of Sindragosa is a level 100 Frost death knight talent.
 * Sindragosa's Fury is a golden artifact trait for the Blades of the Fallen Prince, summoning Sindragosa to breathe frost on enemies.
 * Sindragosa appears as a legendary card for the Mage class in the Knights of the Frozen Throne expansion for Hearthstone.
 * She also appears as a boss in the expansion's single-player Missions.
 * In Heroes of the Storm, one of Arthas' Heroic abilities is "Summon Sindragosa", which causes Sindragosa to appear and fly over a portion of the battlefield, slowing and disabling enemies with her frost breath.