Gold Drop off Event?

Gold Drop off Event?

Is there an event that catches when a unit drops off gold at a town hall? I want to have a random chance that when a unit comes back from the gold mine he will be carrying a rare gem...

Event:
A unit begins casting an ability
Condition:
Ability being cast equal to Return Gold
Random Integer between 1 and 20 equal to 1
Action:
Etc...

Doesnt Work, already tried it
i used Or- Multiple conditions and added all the types of returns.
Also tried changing the event to finishes casting an ability.

Begins the effects? Have you tried all the ability related events, it has to be one of them.

anyone who has tried this before know?

Did you give your peasant an inventry?

No, no inventory.
Its just dropping off normal gold like it does in melee, i'm trying to figure out how/if i can track when it drops off the gold at the town hall.

You said you want to give it a gem when it drops off the resources. If it has no inventry, how can you know if it works or not?

I've realised my opening post is a bit confusing...

I want to have the peasant drop off the gold, it as he drops off the gold that the gem is "discovered" amongst the gold. The gem will be just an integer stored for a multiboard which will be then used as an extra resource.

It's not the gem part i'm having trouble with.