This except stay in UH presence. While this might seem counterintuitive b/c of the 15% damage buff from FP, UP offers 50% faster globals AND faster rune regen, allowing for enough additional howling blasts to make up the difference in 15% more damage, as long as you are in melee range for FS. See below for more info if you're curious.
Maloriak Aoe Thread
Also to answer one of your original questions don't pestilence. You have to sacrifice a howling blast to do this and it's not worth it. See below for more info if you like.
Pestilence vs HB