1. No you put that info in a frame.

Usually I have a frame labeled "init" that just set all the variable before anything start.

BossLife is a variable, it has nothing to do with your mc, and it doesn't matter if your MC has no instance name at all.

Lets say if you create a button and put this code on it:

on (press) {

my_cool_variable += 5
trace (my_cool_variable)

}

then your variable wil increase of 5 each time you press.

What happened visually on the screen (the damage done) is just a illustration of LifeBoss decreasing.

So your duty is to have the two happening at the same time (play the next frame animation AND decrease the variable value)

2. lifefinalboss is just another variable.

Again just set the original value of it in a frame

Life = 200

and then change it in the code on another frame.

The way you will know your game is finished and it's time to go to the "gameover" screen is when you kill your last boss (I suppose)


Off course you can choose to name those variables the way you want. Just don't use spaces in the name or anything dodgy like @#%...