Sanctuary – “Life in death and death in life” [Campaign 4 – Mission 4]

I agree with the last post; phoenixes are very helpful. In the first week, I captured a town. I defeated the Progenitor Matriarch, and now I'm stuck because, according to the Tears of the Phoenix scenario, you can't capture any other towns besides Izergim. I guess I'll have to stay put and build up my army. This is on a difficult setting.