Shooting gallery
Familiar with how to set up a spiral path megabattle? I hope so. If you do the usual work for setting one up, but deliberately minimize the time you spend getting the enemy towards or through the pass entrance, you can end up with a large number of them outside the pass, stretching back towards the tower. When you fly back out there after getting the usual start checkpoint for the megabattle, you'll find them mostly just standing around, though making occasional hesitant movements towards the pass. They're sitting ducks, and it can sometimes be a bit like facing a line of targets in a shooting gallery at a fairground.
Obviously there's major potential for mischief here. You can go to work on them however you like and they won't come after you, except for Elites or Hunters in rage mode. The needler and rocket launcher are great fun here; grenades too. And pistol fans will have a field day! "Step right up folks; knock 'em down and win a stuffed Grunt!". Another thing you can do is fly out here after getting cloaked, for a spot of close-up mischief; tagging enemies, bopping them on the nose, and so on.