0 0 0This achievement requires you to collect the 4 red skulls within Thornvick, you must collect them before you start the battle as they will de-spawn, audio got a bit messed up.
0 0 0When doing this achievement you must remember:You have to collect the skulls while you are sneaking in the forts. When you attack a fort with your army all the skulls are gone!With that being said, here is a text guide for this achievement, http://www.xboxachievements.com/game/viking-battle-for-asgar... and here is a video should you prefer not to read the text guide: