Hmmm... I think you have the ends of the table in roughly the right order (i.e., that Natural Disasters should be rarest, then Military, then Political). I also think you've shifted the ideal point to inject Edge to after rolling the dice. That said, the asymmetry of the table seems to throw things off. I'm leaning toward 7 on the event severity table being "No Event". How about keeping 2 and 12 to being Natural Disasters (positive/negative), 3 & 11 Military, and 4 & 10 Political. That leaves only 5 and 6 to figure out. I like using the 3d6 use two best/worst mechanic, but I think it should be symmetrical. I suppose it should be based on what kind of universe you want, as you've got two dice mechanics to choose from, and two tables (positive/negative). I'd propose 5 be the Military and 6 the Political event, of whichever flavor you want...