Obviously I'm having similar issues. The only one I can consistently get is the "Bleeding Out" one (core overload must be active and you finish with b22). Uppercut I can get sometimes and I've never gotten the Augur lunge one to work.
Tried that and didnt work.mash them together or alternate? And why doesn't it say that in the brutality description. Either I'm missing something or mine is glitched.
I asked the exact same thing a few days ago. Apparently that's how its supposed to be!? Makes no sense to me. It would be ok if the edges instantly froze them but no, they have to stand on top of them for a few seconds.
Arctic Barrage is easily my favorite. So satisfying to use. I like core trap but it seems kinda glitchy. Apparently they have to be standing directly on a laser to get frozen?