you dont have to send out all your troops,there are arrows under each of the troop icons in the command menu that let you decrease or increase the amount of whatever you want to send
to beat the end you should have an 3 angel soldiers at most to hold him off while lots of wizards/dryads/totems are at the back doing crap loads of damage to it if you dont have a angel soldier in front of the end then SPAM HOBBITS to delay its progress