I actually came up against a 4 warrior team with a shaman healer last night. They were in honor gear with vicious wep and went very close to killing my DKs straight up. Lucky for me their timing was not great and a few started bladestorming out of range of my team and I was able to PoH spam enough to keep them up, kill the sham then take them out one by one with hungering cold rotations.

I have absolutely no doubt however that a 4 war team in full vicious that 4 x blade stormed my DKs would kill them even with the PoH spam. The damage is closer to old howling blast where all targets are hit for 100% and is simply unhealable x 4 for a single healer.