U must fight against lil stacks ot shooters. U need in ur army one tank, one dps and one healer.
Also u first need to reach 250 blood rep.
And Heroism, Mass Heroism and Anathema.
Then u must kill almost all enemie shooters, but one small amaunt must still.
And just reapeat, Heroism, Mass Heroism and Anathema.