Sometimes the arch villain of the story is the one pulling all the strings in the background, and the protagonists don't know about them until the endgame.

And other times, the arch villain gets to clash with a protagonist (or an opposing character) that is also a mastermind pulling ...

Having decided that shock value is needed in your comic and you must scare, disgust or generally traumatize your audience in some way in order to get the emotional reaction to serve your theme and your subject matter, how do you decide when and where to draw the line? (note ...