Not sure if this is an appropriate programming question or not; but here goes....
I've written a very simple add-on that displays text/plays a sound when certain spells become usable (Overpower / Revenge).
But I've been unable to find the appropriate event to listen for to check this. My hack-ish approach is to simply check the state of the spells I care about whenever any event is passed to me.
Is there a specific event that I can be using? I went through the docs on WoWWiki and didn't seem to find anything relevant.