Saw your post and decided to work on my SP macros for a while.

This is what I came up with:

/stopmacro [channeling]
/target [harm,nodead] [target=raid1target,exists,nodead] [ target=party1target,exists,nodead]
/assist focus
/stopmacro [notarget]
/use 13
/use 14
/startattack
/castsequence reset=target/combat Vampiric Touch,Shadow Word: Pain,NIL
/castsequence reset=combat Mind Blast,Mind Flay, Mind Flay, Mind Blast, Mind Flay, Vampiric Touch, Mind Flay, Mind Blast, Mind Flay, Mind Flay, Mind Blast, Vampiric Touch, Mind Flay,
/castsequence ,Shadowfiend,,,,,

This works a TON better than what I was using before - try it out and see if it helps. Improve it if possible, I'd love to see it made better!