WAR Combos go something like this

Heavy Swing -> Skull Sunder -> Butcher's Block (Builds 2 Wrath under Defiance)
Heavy Swing -> Maim -> Storm's Path (Single Target) or Storm's Eye (AoE) (Builds 2 Wrath under Defiance)

Wrath V Abilities > Inner Beast (single target) and Steel Cyclone (AoE)

Other abilities you want to use are Infuriate which automatically gives you Wrath V and Unchained, which keeps the hate buff but loses the damage nerf of Defiance for ordinary abilities.

Also, you can build wrath by using Berserk and Vengeance which both grant 1 Wrath each.