In Wrath of the Lich King, Ulduar lets the player online enjoy gorgeous setpieces, sprawling battlefields, and innovative boss encounters. It provides a unique and innovative raid experience and includes additional challenges and rewards for seasoned raiders. So at that moment we avail ourselves of this opportunity to look at some of the new content that makes Ulduar stand out.
   In Lich King, most of the players have already forgotten their feet wet in Naxxramas and the Sartharion raid, but Ulduar is the first example of the expansion's much larger, truly epic scope of raiding, as will be evident from the moment you set foot in the instance. The difference between Ulduar and its predecessors is that the new dungeon actually comprises two separate raid areas. One is an epic battle against a vast army standing between you and the entrance of the dungeon proper; another is that you will dive into the heart of the dungeon itself and finally discover the secrets of Ulduar.
   Without doubt, Ulduar illustrates the new design challenges and innovations that come with the bigger scope of this expansion's raids. In order to make raid content more accessible, a raid has to offer a lot of variety, but it also needs to include a very granular means for players to adjust the raid's difficulty. This concept was first realized in The Burning Crusade with the introduction of Heroic mode, and Wrath of the Lich King is developing the idea even further with new Hard Modes.
Boss fights that have a Hard Mode are affected by certain variables that players can control and change the encounter's difficulty. For example, in order to spread throughout Ulduar's vehicle section, there are four Defense Towers you can destroy. The more Towers you leave intact, the harder the encounter with the Flame Leviathan will be, but the loot will also be better.
Ulduar isn't the first dungeon to include Hard Mode, but it certainly makes the most use of it. Out of 14 bosses, 11 will have a Hard Mode that offers additional challenges and rewards. Ulduar will appeal to a wide range of play-styles and the dungeon has also great longevity and high replay value.
But Ulduar's new master has rallied a massive iron army to guard the entrance to Ulduar and prevent any unwanted guests from reaching the inner sanctum. Thankfully, you'll be able to face the Iron Army on even footing: a small fleet of siege vehicles will be on hand to aid you in the assault.
At that time, you will have to use vehicles wisely to break through Ulduar's defenses. You can freely make use of a mix of Choppers, Demolishers and Siege Engines and each granting unique abilities to the pilot and the passenger. Chopper drivers can create pools of liquid tar that snare opponents and can be set on fire by area effect attacks, while demolisher passengers can load themselves into the vehicle's catapult so that the pilot can launch them into the distance. If used judiciously, these and other abilities will help decimate the iron army and any other threats lying in wait between you and Ulduar.
Overall, we can say that Ulduar will be a bit more difficult than Naxxramas, even without the hard modes. We're going to tune the zone for accessibility, but a raid group that's done Naxxramas, Malygos, and Sartharion and obtained the gear from those encounters should be well prepared for Ulduar. The raid's gear goes better but now players should have some raiding experience under their belts. We have a much more accurate picture of what guilds are capable of healing, damage, and tanking perspective then when Wrath of the Lich King first went live.