Brain variable is the same as the HP and MP, except you can define it dynamically with arbitrary name of it. Such as, you can define a variable called "morale" just use the output channel. After defining it, its value is 0 initially and it can be changed by output channel values.
Channels
bv:<var name> (the XXX is the name of the variable) for example bv:morale
In value mode (default)
The value of morale will be: decision node active * output value
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