It just doesn’t really work, there’s no ranged option, the aoe is clunky and hard to pull off compared to other classes, obliterate works only off procs of killing machine as they give it it’s real damage, but you have no guarantee, you can sit there 10 seconds without one proc. Glacial spikes, your best aoe option costs a bit too much runic power. Your only strength is the 2 target cleave with death and decay and obliterate. Meanwhile Unholy DK covers all these weaknesses and is also much easier to play.
I think frost worked better when you didn’t have to spontaneously switch from single target to AOE, in this xpack many dungeons require spontaneous AOE, which is a weakness to a spec that is 100 % reliant on cooldowns. No icy veins means no damage.