I wrote this macro + plus guide, going over the Rotation.
-Note, This is a ‘scripted macro’ and not a ‘priority macro’ and largely depends on haste, otherwise abilities are stuck waiting on specific runes. Single target rotation
The Video can be seen here: http://youtu.be/WkxiE2VPHb8<
/castsequence [mod:alt] reset=8 Horn of Winter,null
/castsequence reset=target Plague Strike,null
/castsequence reset=0.5 0,Death Coil
/castsequence reset=6 Festering Strike,Scourge Strike,Scourge Strike
This command clears the red error text as a separate macro:
/script UIErrorsFrame:Hide()