I haven’t seen anybody post about this yet, so I will take the liberty of doing so. This is my full single-target rotation for Affliction with Decimating Bolt and Drain Soul. Actual dot application order can vary.
Refresh Agony.
Cast Decimating Bolt.
Apply Agony.
Apply or refresh Corruption.
Apply or refresh Siphon Life.
Apply or refresh Unstable Affliction.
Cast Phantom Singularity or Vile Taint.
Cast Summon Darkglare.
Cast Dark Soul: Misery.
Cast Malefic Rapture with 5 soul shards.
Cast Malefic Rapture while maximum number of DoTs are ticking.
Fully channel Drain Soul with Decimating Bolt buff unless a boss mechanic is going to kill you.
Channel Drain Soul as filler.
Enjoy 