Folks at Games Workshop love to put skulls all over anything. We in Central Europe understand their liking. It comes from an ancient Christian invocation: Terminus nulli cedo - The end (Death) bows to no one
A swamp and its family and relations are rarely seen and that is a pity as they offers interesting strategic challenges. Seem to favour static armies with a lot of guns where in fact it can also become a deadly trap if the enemy manages to outflank you?