Um Im stuck on the fortress which you have to attack wit da rats

use your tunnellers and wall climbers first. while shooting the wall down with a warp cannon and then send in the stormvermin. take each part one by one not at once

move your army as far back from the castle as you can put the cannons up front and take out the empier cannon on the near tower and then the walls coz if the cannon is takin out they cant damage your army when you charge then use the cannon to take out the units that try to charge you. also when the wall is down fire a the archers on the wall coz they have less range than the cannon so they cant hit it but you can hit them

this worked for me coz your army dosnt get touched and you can take out lots of there guys and still have a full army. but the most important this is to take the empier cannon first coz thats the only thing that can take out your cannons. hope it helps