So this was my first tutorial I made a long time ago haha so it's not super perfect but it might help with a few others things when it comes to spawning random stuff. You also should create a family and name it something like enemies. Add your enemies to that family and then give that family an instant variable (number) call it enemy hp. You then can set each enemy with it's own hp. even if all of the same one's are on the screen it will only take hp from the enemy that's hit. Do something like enemy on collision with player bullet, subtract 3 from enemies hp. As I said it will only take hp from the enemy that's getting hit with the player's bullet. Then have an event when enemies hp (this is the family hp) is = to or less than 0, destroy! Hopefully this helps and good luck!!!