Unholy DK

I’ve just done a 2s game against an unholy DK and the damage was crazy. I’m not complaining about the damage, but as I haven’t seen that dmg before from a DK I don’t know what I’m looking out for.

He gripped me off that bat and popped CDs, my priest gripped me back and we hid. He came to us, chunked my health causing both me and my healer to have to pop CDs. We recovered and what felt like within 30s the dmg was back to the same level. I didn’t see any CDs popped, my healer was out of cc and healing me, but was too much.

What am I looking out for against an unholy dk. What do I need to LoS, CC or pop my own CDs on?

As I said at the start, this isn’t moaning about the dmg, this is trying to understand where it came from and what I need to do to counter (for reference I’m playing destro).

Ta