I am just guessing here, as I did not use this script yet, but here is how you could do it:
First make your effects in the database.
If you want to remove/deactivate something, you just make a "Remove XX" effect instead of an "Add XX" effect.
In the case of buffs/states, you make a "Remove X buff/state" effect.
In the case of lowering something else, like stats and params, just use negative values.
In the case of a common event, well, you specify that within the common event itself the same way.
When you are done with the effect setup, you can make the conditions for them in the note-tag field.
The example note-tag on the picture here means that the second effect on the list (effect count starts from 1, and goes from up to down on the list), which is "Add State: Death", will only be executed if the actor got the state with ID 10 inflicted on him/her.
By going with the logic, you can make any kind of condition for your effects, as long as you know the formula for them.
And just by writing this down, I think I can make good use of this script in some more brainstorming boss battles. So, thanks for the script!
