The gates on the top floor are closed. How on earth do you manage to close the gates on the first floor. It is IMPOSSIBLE to keep the invaders off the wizard. I have my creature summoned and I have summoned a demon, but I cannot protect the wizard long enough for him to close the gates. I have had the game running for 5 hours and am about to give it up. The only thing I have gotten is 5 levels from all the fighting.

Can someone tell me how to get through this section.