I had killed 6 Viking enemy troops in a row. In each battle i killed a stack of the unit "viking" (not to mistake the troop berserker, they don´t count, all other viking enemy units also don´t count) with a attack of a valkyrie.
Not a Viking rage attack from the first row. They don´t trigger the medal. You can use any attack from the second or third row (the "valkyrie" attacks). 6/10 so far after these fights.
Each fight you can get only one timer of the medal, i have killed 3 stacks of the unit "viking" in one fight with a valkyrie, but it only counts as one.
I hope this is a bug and it should be "any" enemy viking unit and it is wrong that it had to be the unit "viking". Or there are many battles against vikings later
