Warcries are a varied skill tree in the Barbarian's arsenal. There is a lot of variety in this tree, ranging from attack skills to aura-like bonuses to corpse skills. There are actually seven Warcries in the skill tree, the other three are corpse skills, grouped in here by default.
Warcries are cast with a right click, and are a sort of spell. When casting them the Barbarian throws his arms up and his head back and howls. The warcry is shown as a nova of brightly-colored light moving out from the Barbarian in an expanding ring. All warcries have a distinctive graphic, but the sound the Barbarian makes is a random one each time. The Warcries all have different ranges, with the beneficial aura-like ones generally going nearly full screen, while the attack Warcries that hurt monsters have much less range, usually just a few yards.
Other characters and minions must be in range of the Warcry when it is cast. Walls and other solid obstacles block Warcries for anything behind them. Duration of the buff depends on the amount of skill points in the skill. Beneficial Warcries can be refreshed before they expire.
The three corpse skills are very useful as well. Find Item is one of the most powerful skills in the game, in terms of finding good equipment, and Find Potion can be very helpful also, for the more patient Barbarian. Grim Ward is used to keep enemies away from an area, useful if a Barbarian needs space to escape dangerous situations.