Don't rely on events unless you don't have any scripters, which is not the case.
I'm not quite sure I get you, I'm sure what you're saying makes sense, because why make a script to make a door open when a few enemies are dead, like the only way I can see it is onActivate>Player>EndLevel. You would be
perfect for Head Scripter, Nexus, you understand the most efficient way to pull this off.
Oh, and Uxie, just model the 1x1 Round, that appears to be more popular.