Fallen Captains. The second Overload Champion is bugged, and doesn't stay stunned.
Barrier Servitor that shields enemies. It frequently teleports behind cover.
Void Servitor in the boss room that shields enemies. You can get away with ignoring it and focusing only on the boss. It seems that if you kill the first one, another will spawn in a later wave.
Arach-NO! – When defeated, Fallen Vandals spawn a web mine at their feet.
There's a wave of Exploder Shanks when you jump across the gap before the boss room. The boss is a Fallen Captain that teleports around.