Revived

I played for 7 weeks, reached level 25, gathered about 180 vampires, and generally felt pretty good. I was about to finish off the green faction. But then another red player showed up – it was Grol (level 18) with 6000 imps (who immediately drained my mana), 666 knights, 150 succubi, and other creatures. He easily defeated me in my castle. I don't understand why this is necessary; how am I supposed to play?