So i know the more abliities of one type you have on your bar, the faster that skill line will level. Example, 5 storm calling abilities slotted or 5 nightblade assassination abilities will level faster then having one slotted.
But what else affects it. Does landing an attack with a specific ability level it up? Do you have to land the killing blow to get it? How can you power level class lines, what is the max level for an ability tree? What is the max level for one ability?