Working on the Traverser of Shadows came the issue of whether he should be given the ability to directly tap into the seeming through use of an old rule in 2e, called a Seeming score (found in the Blood Spawn and written by Ed Stark). Creatures could produce outstanding effects through their ability to control the Seeming and, should other people not perceive them for a supernatural change of what things are, use them against others.

Originally posted by "The Seeming in Play"
Nothing in the Shadow World is as it seems. At least, that is the accepted doctrine. It is untrue. Everything in the Shadow World, which is governed by the law of Seeming, is exactly as it seems.However, what a thing seems to be may change without notice. That is the true
law of Seeming.
In other words, if something changes through the power of the Seeming, it will be thus unless you perceive it for what it trully is.

It is rather obvious that this should be included in the Atlas. However, there are other issues that arise from this fact: how should Seeming and Perception scores be handled? And how should the two be used?

One could easily assume that Charisma affects one's Seeming score and Wisdom affects one's Perception score, but other than that...