"The Gathering Storm offers six campaigns, more than 20 maps, 16 additional artifacts, four new creatures, and a multiplayer update. Each of the first five campaigns features a new specialty hero. The Gathering Storm also features an upgraded editor, which allows full access to new heroes, adventure objects, artifacts and creatures. A new music soundtrack is also included."
Source: Wikipedia, "Heroes_of_Might_and_Magic_IV," available under the CC-BY-SA License.