Lord of Sausage is right. Starts the effect of ability is possibly the best way to reference when a unit starts casting an ability. I use it all the time for triggered effects, and Lord of Sausage is really great with triggers, so you're in good hands in that regard XD.
Also does anyone know an ability that i could change that would do nothing to any unit, and it cost's gold?
I'm told 'do nothing' leaks, and besides that's where you'd want whatever effects the spell should have.
Whoever told you that must have been smoking something.
"do nothing" actually does "something", namely putting a new function on the call-stack, but nothing that affects gameplay happens. Therefor, you shouldn't use do nothing because it slows down your computer without actually doing something. But it has nothing to do with leaks.