Here is what I notice:
1.) In the common event options, you are telling the event only to begin when Switch 1 is on, however, in the If branch you are turning switch one on, you can't turn a switch on when it only begins when the same switch is on.
2.) Completely erase the "Call Script" pieces, I will explain why later.
3.) Since it is a Boss Battle, place the event on the Battle Map. Since Common Events are events that are mainly used more then one time. But from what I can see, you are only going to be using it once, or on the battle map.
TIP: You can see if the variable increases as the monster dies by going to the Debug Menu (F9) in test Play Mode.
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Here is how I would go about doing this:
1.) On a new event on the Battle Map, set the Trigger to Parallel Process.
2.) Create an "If" Statement where if Variable X (X = Your variable) is equal to one so and so happens. Else case is not needed, as if you put a message in the else case the message will keep reappearing, unless you create another variable and If branch to see if the message was already sent and then not send the message, but I won't be explaining how to do that.
3.) In the "If" Branch use a Switch Operation and turn Switch X (X = Your switch) on. Now this is what I like doing, but you don't have to do it, erase the event.
4.) Now have a portal looking sprite on the map somewhere which appears if Switch X = True, then if the player walks over he/she is teleported.
Here is what the final event looks like:
Check Event
Portal Event.
Cheers,
Syn.