Bornakk has released details of the Crusaders' Coliseum dungeon that will be introduced in patch 3.2. The coliseum will be located on the Argent Tournament grounds and will contain an epic 10- and 25-player raid dungeon with five encounters that are unlocked one week at a time, as well as a new 5-man dungeon. The raid will have four different difficulty levels: 10-man, 25-man, 10-man Heroic and 25-man Heroic.
The coliseum will also introduce the Crusaders’ Tribute system. According to Bornakk, "Each of the Heroic mode instances has a new tribute system that will limit players on the number of attempts they get in the Coliseum each week to present a greater challenge for the most battle-hardened heroes. Additional rewards can be earned depending on the number of attempts left in the tribute run each week when the final boss is defeated."
A new tier of armor and weapons, which appears to be Tier 9, will be available in the coliseum. You can discuss the Crusaders' Coliseum in this thread in our general forum. Bornakk's full announcement can be found below.