Try it the other way around. Start with the protagonist, spell out his goal and his conflict:

“A young Aborigine must stop a white man using tribal magic to murder people with their own shadows.”

Stopping a killer is enough of a necessity that you don’t need to mention the end of reality in the logline. In a synopsis, sure, because you can spend a couple sentences explaining what that means. But you don’t want people asking questions in response to a logline because they don’t understand it — you want them asking questions because they’re interested to know more.