I tried using the Immobius, it's alright, has a nice fire rate, but I don't see why you would use it over Invective, or Conspiracy Theory-D if you want the other archetype. Any super offensive Titan is running Armor of Light, which is where Immobius shines. However, 90% of the time you're using it outside of your bubble, so the perk doesn't really come into play too often. Fabian Strategy would be good if they didn't scale the damage down when the rate of fire went up. It's just an odd auto rifle with a less than stellar design and throw away exotic perk.