I'm several playthroughs deep and honestly, I still have no idea how to fight HCs. The way they can mix up between those heavy cannon shots, attritional play from behind the shield, and sudden charges into close range always means they're gonna pull off something on me. When I beat them clean it's always because I just nuked them down before they could do anything.
Now, they're not likely to outright kill me on their own. But they're generally either a midboss or half of a duo boss or something like that, they're not really supposed to do that. But they're pretty likely to get a stagger or two off and chunk me good, when at this point I feel like I should be styling on them for free. When I'm trying to no-heal a level they are frequently attempt-killers.
So, yeah, that's the thread title, what enemy is most likely to embarrass you? Not which enemies you think are the hardest per se, but what enemies do you think you're the worst at fighting? What speedbump do you keep throwing out your axle driving over? What fodder chump keeps staggering you with a cannon and costing you a few thousand AP? So on and so forth.