As the Watcher, if I want to activate a hero's limit, I have to offer a PP first, otherwise spend a die from the doom pool. That seems reasonable enough. But if the limit gives the player a PP (looking at Iron Man's Power Surge - Shut down highest rated power to gain 1 PP), do they get an additional point? Or Colossus' Heavy Metal limit. If I hit him with a big magnetic attack, the player has the option of invoking the limit? Or does it happen automatically? And if so, does that give 1PP for the Watcher invoking, and 1PP for the limit itself?
On an unrelated-to-mechanics vein, do many of you Watcher types invoke player limits? It seems like a quick way to put the fear of the doom pool into some players. Obviously, it has to make sense narratively, but I can think of all sorts of scenarios that start screwing with powers by invoking limits, rather than tacking on complications. The nice thing (from my perspective) is that a limit can't be bought off as the result of a great roll bought up with PPs. They are stuck until the Watcher rolls an opportunity.
