System mastery is fairly straightforward in its meaning. It is a feature of Dungeons & Dragons and other gamist RPGs, a reward for sticking with the game and learning the ins and outs.
At various times I have obtained system mastery. I had it in D&D 3e, and Magic: The Gathering. I had it in Counter-Strike and Battlefield 2. I now have it in HTML and CSS and general internet stuff.
Lately, however, I am realizing I have system mastery somewhere else, and it is really giving me a boost. My realization corresponds with Emma becoming more interactive, as well as meeting more people after the hibernation that is very, very early childhood.
It is hard to put into words, but it is something akin to waking one day and realizing I am doing okay, and have the ability to help others. Never mind, that was it. I am doing okay. I can help others.
It is all going to pour out soon. ^_^