They get a weakened down version of fly, which allows them to get to areas that would need to fly. It would cost 50 mana initially to use it, reason being that it takes concentration to do so. Also it would take an additional 10 mana per movement square, and the movement would have lag on it, 1 tick. If the Drow is attacked during this time period, they no longer fly. They also cannot levitate if their adrenaline is still gushing.