Well pre mistlands i would say Swamp. it would be the most challenging if this is your first viking. Plains the squitos will get you the first couple times, or a lox will chase you up a mountain. Now with mistlands...I havent died there yet because I was paranoid and prepped but yea its a nightmare. Especially before the very needed balance to the ants, parry smack them with frostner and they acted like it tickled smh.