|2 people marked this as a favorite.|
As a rule of thumb, when I know someone has run, read, or played the scenario I tell them, in front of the rest of the players, that they are banned from making or suggesting decisions. Those are my terms to play at my table if you have prior knowledge of the scenario.. your character goes along with whatever the majority of the rest of the table wants to do. When I (and the plot-spoiled players) know something dicey is up and potentially can be broken in-combat by their knowledge (that encounter you're talking about, but also others like the BBEG fight in Master of the Fallen Fortress and so on) I force them to ask the table about what they want that character to do.
So, in a case like the one described in the OP, I make the plot-spoiled player ask the remaining unspoiled table what they want his character to do. If it's to do something that the spoiled players know is a bad idea, then so be it.