This is the same as the above, except that it casts your only casting time DoT to start. This is recommended when grinding. As you can see, the order of the spells is simple to change, and can be changed to match your personal preference.
#showtooltip
/cast [modifier:alt] Amplify Curse
/stopcasting [modifier:alt]
/castsequence reset=Target/Combat Unstable Affliction, Corruption, Curse of Agony, Siphon Life