"For Each" loop is working and it does process each of the Brain instances.
The problem is with the sub-events. I believe you need to reset the variables to their initial values (x=4, y=0, z=-1) in event #36.
Alternatively, you can move variables declaration inside the "For each" loop, then they will be reset automatically.
You might also want to reset them in between "Repeat 30 times" and "Repeat 16 times" loops.
The "mutate" variable always equals 5, so all events with condition "mutate<=2" will never work.
There may be other mistakes in those loops, I really don't understand what are you doing there.