Detect When a Unit Hits a Tree?

[the_ideal]

I have a peasant with a custom gather ability that takes 0 life away from the trees it hits, and I want to trigger it to add lumber on every strike. I used "Unit Starts the Effect of an Ability" and set condition: (Ability being cast) Equal to Harvest (Peasant Custom). But the trigger doesn't fire.

I know I can use an order string, but then the player could spam click the tree to get tons of lumber.

Solutions?

+rep to anything helpful, and thanks.

 

[LiVam]

Why not just do "A destructible dies" as the event?

 

[the_ideal]

> Why not just do "A destructible dies" as the event?
"gather ability that takes 0 life away from the trees it hits"
"I want to trigger it to add lumber on every strike"