My rotation is as follows.
1) Round up as many mobs is feasible given environmental surroundings
2) Icy touch, Plague strike, Pestilence one mob
3) Cast Death and decay
4) Cast Icebound Fortitude (1 min CD for 20 runic power, why not?)
5) As runes come back Death Strike anything that is alive more so for healing purposes rather than damage. You can get 2 Death Strikes easy which should heal you to full
5) Cast Unholy Blight if you have the talent/have the runic power. Can have it up to finish off mobs or be ready for the next group
6) Repeat
I cant say which presence I like up more, Frost or Blood. If you utilize Icebound Fortitude, I am leaning blood so the mobs drop faster. Dont use unholy presence. 1 sec GCD not needed since you blow your runes really fast as is. And I dont think blood boil is worth while considering the low damage it gives and does not let you Death Strike for health.
Just my 2cp and it works great with no healing downtime.