I have three rotations set up, but basically only use two.
They are all priority sequences.

My Obliterate is not set up at all like Mosg2's.
It is a straight priority sequence, with Hungering Cold manually controlled on its own key.
And when I spam the OBL sequence key, everyone does the single target sequence.

They function the same as Mosg2's method.
More keys for the abilities you want to fire off the most often.

HB: (On "spam 1")
HB > FS > NS > BS

OBL: (On "spam 2")
OBL > BS > FS

I have a key for Outbreak to place diseases on my target, before the Obliterate sequence, as that increases Obliterate damage.
Swarms of hordies fall to this, if they're too much for me to heal through.
If I can heal through their DPS, the HB rotation is AoE damage and will kill them faster.

Obliterate seems to hit like a truck on low armor/stunned targets.
HB seems to be better against high armor targets, the HB component might be a spell that bypasses armor?