The following three Achievements can be completed in Campaign or Horde.
Stop Hitting Yourself
Gamer Score: 5
Kill a Guardian or Sentinel with a Guardian or Sentinel weapon. Down a Guardian or Sentinel and pickup its RL-4 Salvo or Tri-Shot Heavy Weapon. Now down another one of these aerial Deebees with that weapon to earn the Achievement.
Pounsus Interruptus
Gamer Score: 5
Kill a Pouncer mid-pounce with Shotgun or Chainsaw. Pouncers are encountered in the Campaign and Horde modes. Get the Pouncer’s attention while it’s atop a piece of cover, back away from it a few steps to bait it into leaping, then rev your chainsaw. If things go well, you take down the Pouncer and earn Pounsus Interuptus. Watch out as it may throw its quills in an attempt to stun you.
I Live. I Die. I Live Again!
Gamer Score: 5
Rescue someone from inside a Snatcher. The Snatcher appears in the Campaign as well as a random chance in a Horde Boss Wave. If a player is DBNO near the enemy, it snatches the downed player and swallows it whole. Concentrate gunfire on the swollen stomach until the teammate is freed.