Don't forget that you can use a macro for your spam key:

Mine is something like this:

/castsequence [target=party1target,harm] reset=combat Immolate, Curse of Weakness, Shadow Bolt, Shadow Bolt, Shadow Bolt, Shadow Bolt; Immolate, Curse of Weakness, Shadow Bolt, Shadow Bolt, Shadow Bolt, Shadow Bolt

This way you get in a DOT and a curse before you start spaming direct damage.