Frostwing Halls, a chilling place containing the final obstacles between your raid and the Lich King himself, is now open. You can expect to uncover disturbing and horrific phenomena taking place against the Green Dragonflight before finding Sindragosa hovering above you. Should you have what it takes to destroy the Lich King's most prized frost wyrm, as well as having already conquered the Plaguewerks and Crimson Hall areas of Icecrown Citadel, you'll have your chance to follow Tirion Fordring to the Frozen Throne, a chilling pedestal atop which the Lich King has reigned unchallenged for years. The time has come, brave adventurers, for him to fall!

For more information, read the full 3.3.2 patch notes.
http://www.wow-europe.com/en/patchnotes/