Wizard – “Hope of Zephyr” [Campaign 6, Mission 5]

My problem is this: I take the city of Biara without any issues. However, the Elves suffer losses. Then I take the Shield. Everything goes smoothly, but the Elves still suffer losses.
I take the city... and then comes a sea of sadness and disappointment. It seems that 40 Ents, 100 Druids, and 20 Dragons should be enough, but no! 10 Devils, 15 Dragons (skeletons), 100 Demonesses, Pit Lords, dogs, and horses wipe out my entire army. In the end, the situation is roughly like this: 10-9 of my Ents against 5 Dragons, 5 Devils, and 20 Pit Lords. I'm thinking: Maybe I should drop a couple of Dragons on Raileigh before the assault; I'm doing well with him. Enhanced Shock Earth and Meteor Shower (I don't use Armageddon) don't... wouldn't let the Overlord get bored! So, what do you think?