Cradle of the North level: (see walkthrough. item 12, preparing for battle) Put towers everywhere between the world seal and your camp, and upgrade them ( frost-towers). Put towers around the idol northwest of the seal and upgrade them. Keep your army just north of your camp, between the mountains, ready to defend. Put your scouts flag between the idol and the world seal; When the black shades appear, they will attack them first (with al little bit of luck), and then the towers start fighting, then the shades will fight the towers! Try repairing the towers as much as you can. If you have enough towers, they wil not even reach your camp! ( if neccessairy you can repeat this trick with towers just south of the fishermans house.)