Best way to execute a destroy command only once?

What I want to do is, when 2nd wave is reached, that is enabled by reaching a certain score, all enemies in the screen are destroyed.

But after that, I want the spawning of the enemies of the 1st wave to continue the way they were.

I'm adding "If score > or = than X, Enemy Destroy"

But they never spawn again after that.

Tried with subtracting all health, didn't work either.

Any suggestions? Will I have to create a whole new spawn event for each wave or can that be done simply?

Can you post a screenshot of your spawner code or a .capx.. would make it much easier to figure out what you're trying to do.. I can think of several ways to do this (and did in my space shooter) but it seems you have a certain way in mind.

I think a trigger once will do what you need if I understand correctly.

Whats happening at the moment is once you are above a certain score you just keep destroying enemies every tick, if that makes sense. Even a Boolean that you set to true once you have destroyed the enemies could be set and referenced in order to control it.