is this a scripting thing? if so, anyone know
how to set it up? (once again scripting is preventing me from releasing a map)

Yes this is a scripting thing. It is not very difficult to do. You just need to have a trigger on a function call that checks if a given hero is still alive.

There are some examples on this board. Check it with a search. You can also try to dig into the resources of the game to extract the code snip set.