Warmachine: Wrath is the first expansion of Warmachine since the launch of the game's second edition which is known as MK II.
Wrath introduces an entirely new model type; the battle engine. Battle engines do not replace Warjacks or Warriors, but instead provide players with survivable, concentrated firepower and a wealth of tactical options that will appeal to a wide broad range of playstyles.
Wrath also introduces another new model type; Ranking Officers. Ranking Officers give players more reason to field Mercenaries in their armies. They provide all the benefits from a typical unit attachment, but they also transform their Mercenary units into faction units subject to all of the spells, abilities and feats the faction has to offer.
Of course, Wrath also contain new models for all the different factions.