Ability Turn Off Event?

How can I detect when an ability like Immolation is turned off? I've tried using EVENT_UNIT_SPELL_ENDCAST and EVENT_UNIT_SPELL_FINISH but they both trigger upon activation. Please advice.

EVENT_PLAYER_UNIT_ISSUED_ORDER
Check if the order is unimmolation's.

Thanks for the quick response I will try your method. +rep.

Of course, mana can also cause it to turn off, etc. I find that waiting until it no longer has the buff is the most accurate and pain free way.

I agree with CG about the buff monitoring (That's how I do it in maps), but if you strictly want to detect the instant of turnoff then there's no more accurate way than catching the order.

Thanks CG, I didn't even think about that. I will use buff monitoring too. +rep.