What REALLY helped turn the tide (with Necrons literally at the walls of my capital) was the most blatantly OP unit I've encountered so far: Scorpius Disintegrator. Kills everything, never dies, and is more economical to field than the Knight Questoris. These fellas, with the help of Manipulus and a few friends, helped beat back the Necrons and destroy at least one of their cities, halt the Orks, and then crush the final mission onslaught without any real casualties.
