-In Challenge mode, use Tyrone and have the enemy follow to the bottom right corner of the level. There is hut-like structure here. Go under it and jump off to the cliff side. Dash back on top of the hut. When the enemy follows, freeze them in their Dash to make them fall to their death. You can easily get the Challenge mode achievements by doing this.
-Use the player Mousey McNuts in Challenge mode as he has great secondary fire that shoots bullets from both sides. Get near the enemy and press LT to fire the secondary weapon. It normally takes only two shots.
ACHIEVEMENT - HOW TO UNLOCK Completed Training (10 points) - Complete Single-Player training mode. Combo x2 (15 points) - Kill two opponents in rapid succession. Combo x5 (20 points) - Kill five opponents in rapid succession. Challenge x15 (10 points) - Defeat fifteen opponents in Challenge mode. Challenge x50 (25 points) - Defeat fifty opponents in Challenge mode. Won 10 Matches (10 points) - Win ten matches in Single Player or by playing on Xbox Live. Won 50 Matches (15 points) - Win fifty matches in Single Player or by playing on Xbox Live. Won 100 Matches (25 points) - Win one hundred matches in Mission Mode or Battle Mode. Complete Mission Mode (20 points) - Complete Mission mode. Played 100 Matches (25 points) - Play 100 matches either offline or on Xbox Live. Marksmanship (25 points) - Score 10,000 in the Shooting Range. Six Degrees of Small Arms (0 points) - Obtained from a special player online. Honorary Barbarian (15 points) - Complete Mission Mode playing as Ivar or Gullarp. Barbaric Recruiter (20 points) - Host an online match using the Iceberg or Village level.