The Rule of Threes
"Good things come in threes," they say. Well, so do bad things. Either way, the number 3's important - some say it's got power. Things out here tend to happen in threes, like Prime Material, Inner, and Outer Planes; Good, Evil, and Neutrality; Law, Chaos, and Neutrality; even prime, planar, and petitioner. See two things and ask, "Where's the third?"