Bungie has been teasing that Destiny's upcoming expansion, The Taken King, will have the "biggest raid" that they have ever created. The raid, titled King's Fall, is so intense that, "it's got its own bounties, it's got new activities." This massive raid might be one of the biggest highlights for the $40 expansion, but you won't be playing it when The Taken King releases.
According to The Taken King director Luke Smith King's Fall will not be present in the game at its release on September 15th, “It's not going to be available on day one. We definitely have a plan for when it’s going to be available."
Smith did not go on to even give a hint at when the raid would be available, but he did assure fans of the game that Bungie would give them fair warning of its release, "I promise for people who are excited about the raid will know when it's time to take time off work. We’ll give em’ a heads up.” King's Fall will take players against Crota's father, Oryx, as he seeks revenge for players killing his son (about 9,000+ times). You can find more details (like the new mode) on King's Fall here.
[IGN]