Pathological focus of will

Something shimmered like oil on water in the corner of Saxon's vision and
he turned toward it in time to see a shape emerge out of the air, a
glassy, swift figure blurred by motion, abruptly becoming solid, real.

The military called it "mimeoptical active camouflage"; Saxon wasn't up on
the full technical specs for the augmentation, but from what he
knew, the system used a matrix of molecule-thin induction wires implanted
beneath the epidermis and across cyberlimb plating that when
activated, generated a local electromagnetic field that could render a human
being into a walking stealth weapon. It was prohibitively expensive
and delicate under battlefield conditions, and difficulties with the human
augmentation interface meant that it was rarely deployed in combat.

Full synchrony between the user and the system was hard to achieve; to use
it well, you had to be someone with a near-pathological focus of
will.

- Deus Ex: Icarus Effect, Chapter 4 pg. 110