I DO have a bunch of ability ideas, BUT I'm not sure what you want to do. We don't need to use a "works-for-everything" ability depending on the conditions of the ability. I need to know how exactly the ability is supposed to work, which includes any durations and conditions (ie is this a buff, a passive, is it permanent, or does it have a duration etc etc etc....). Then I can better help you out. There are a few ways to set this up but I gotta know how you want it to work more than what you've told me because there are short cuts and certain ways in which we set this up in order for it to work properly. Abilities that revolve around a hero dying, other than stock wc3 abilities, require a lot of thought and planning in order to work properly and run smoothly.
For example, just basing this off a unit dying might not be best because if they aren't really intended to die, then the enemy still would gain experience and gold and the death message would still display and all that jazz....unless you had a custom hero death system and bounty system, and all those effects, which normally occur on their own, are triggered instead.
So basically, I need to know what you want for the effect, because we might not even need that or any triggering to make this work the way you want it.