Complete "Pyrrhic Victory", "Old Wounds", "Time And Fate", and "Suffer With Me" in Veteran.
I Don't Think They Exist
In TranZit, kill one of the denizens of the forest while it is latched onto you.
Awaken the Gazebo
In Buried, Pack-a-Punch a weapon during round 1 with no one using the bank or Weapon Locker.
Master of Disguise
In Origins, use Zombie Blood to revive three players and activate a generator in one game.