I'm using:

/castsequence reset=target Icy Touch,Plague Strike,Blood Strike,Death Strike,Scourge Strike

I used to have Death Coil and Blood Boil in there at the end but DC would fail over and over if I didn't have enough runic power due to misses/etc so I keep that on a second button now - but mostly now I just use unholy blight instead since it does good damage, GREAT aggro, and its AoE. Thinking about adding Blood Boil in at the end, not sure if I should keep that on a second button also or what. Advice appreciated.

I also use Death and Decay just after Icy Touch (or just before, your choice, after will make the mobs get hit more).