It is the lone element of Stuffamancy, and also influences Hippiemancy, Naughtymancy, and Stagemancy. Matter is expressed as the disciplines of Dirtamancy with Erf , of Changemancy with Fate and of Dittomancy with Numbers.
The axis of Matter deals with the reality of a thing. When used alone, it affects the Stuff of Erf itself: shaping it on the Erf axis, changing it on the Fate axis and duplicating it on the Numbers axis. When added to Life, it can reveal and modify the way that units interact with the world. Flower Power shapes the way life interacts with non-life, growing plants and preventing Stuff from harming Life. Signamancy changes the Fate of life by modifying the way it looks, and thus the way it is. On the Numbers axis, Life and Matter show how well things interact, allowing for optimum paring.
It is not clear if there is an equivalent equation to the Real World E = M * c * c to convert between Energy and Matter. In fact, since Erfworld has three elements, that there is a more complex equation.