/script SpellStopCasting();
/cast Flash of Light(Rank 3)
You can change the spell rank simply by changing the number to that rank. What this macro does if used properly is you'd re-hit the macro just before the spell completes, the spell will auto-complete itself and it will immediately start casting again with no delay. It'll take a little practice but once you get the hang of it you can do it in your sleep.
