How do I test if something exists?

In my game I have an action that needs to occur when all the sprites of one type are destroyed. I've tried different stuff like "is on-screen (inverted)", but none of it worked. Does anyone know how I can do this?

Thanks in advance!

Compare two values

Object.count <= 0 -> action

Note that this will run every tick as long as theres 0 instances.

Thank you!