Every enemy has at least one defense, yes. Husks and Abominations are Armored.
I basically did figure 8 laps around the room while letting them pile-up on my cohorts, who I had to revive three times(six gel, two at a time.) Miranda and Kasumi, so I had quick-cooldown-Slam for unarmored, Warp for armored, and Kasumi's flashbang grenade for both. It also has decent AoE at less than max rank and randomly causes CC(stunned/dazed), which auto-kills any Husk regardless of defenses left, life left or difficulty. I used Incinerate on cooldown and Sniper Rifle shots(the time slow helps immensely to reposition, refocus and this applies triply so to actually hitting the Reaper Core) in between.
I died seven times, always due to traffic backing up. You literally can't move when you're surrounded by physical bodies, whoddathunk.
I guess my Heavy Weapon Choice could have helped, but not this time. Collector Particle Beam compliments Infiltrator well for self-sufficient "Can Deal With Any Defense", Barriers and Shields extra-fast in this case. Didn't feel like reloading, especially since everything prior to the final room is easy-cheesy power-spam while backing up.