WE recognizing an ability used

How can I make it so the WE recognizes that a unit has used an ability, such as Detonate?

I.e: (fictional trigger..)
Unit uses ability
Ability = Detonate
action =blah blah

pls no FT comments on what the WE can do..

Events
-A unit owned by player 1 is issued an order targeting a point
Conditions
-(issued order) equal to Night Elf Wisp - Detonate
Actions
-whatever

don't work. if the wisp is issued the order to detonate on the other side of the map, the trigger would go off.

Thats why u use ability button clicked or a ability without a target.