I agree it truly is ridiculous to face so many surprise turrets in updated Arms dealer. XD
But I've only manage to build up the practice to handle that with the best gear to tap them out, but what's amusing is watching -blam!- guardians forget the starting elevator of surprise surrounding turrets and getting shot down.
Ah yeah, I had that before. I always run to a corner to hide behind and watch the other two end up shot down again. Not to mention the last phase is really messy, turrets in all around the map.