Special Abilities.
Special Abilities are any kind of power that doesn't fall under traditional spells or perks, isn't a physical item, and is powerful enough to be traditionally ranked. This includes the special powers of Dead Apostles but it would also include things along the lines of Doctor Heartless's instantaneous spatial movement.
The cost spread is the same as equipment and looks like this:
E-rank - 2 AP
D-rank - 4 AP
C-rank -6 AP
B-rank - 8 AP
A-rank - 10 AP
While special equipment are allowed a main function or ability that gets stronger the higher the rank, special abilities are allowed multiple interrelated functions, be it a technique or unique mode that become available at higher ranks, but with a cost. This may not just include something like a Prana or health costs but limitations on usage or conceptual weakness for your character. Compared to equipment I am granted a little more creative freedom for how you can design your powers simply because this is such a broad concept. Generally though, your ability will have 1 to 3 subsets ranked the same as the rank of your ability.