Activation Layer
The activation layer is the layer of the rune where the rune is activated, that is, where the block you click on is located. Runes that are only a single layer only have the activation layer, while three dimensional runes usually have the activation layer at the very top or bottom of the rune. While a few runes have more than one block that can be clicked, the activation block is usually the block in the very center of the activation layer.