As you all might know, being dead does not mean being unable to die again. What happens when you die twice? Nobody knows, but everyone is fairly certain that an after-afterlife is utter rubbish and an absurd fairytale.
What is certain is that being lost in Niflheim, the land of the dead, is inconvenient. A group of wizards learned this the hard way. So in order to get out they devised a plan - to go up and see if they can get out that way. With neither a rope, ladder, helicopter or multi-purpose ascension ointment, their only choice is to try to build themselves upwards... using the bodies of their friends!