13B was somewhat suprised to see that despite the rock, the creature was at least to a point, organic. At this time however, it was not the time to analyze what it was but to time to reduce or avoid the impact that the things massive arm would inflict. In a gambit she hastily ran the opposite direction of the swing and once it got close, lodged the spearhead of her halberd into the arm of it. The maneuver would have likely knocked the wind out of a human though lucky for her, she wasn't. She hung on, planning to start sprinting for the head the moment the momentum from the arm had stopped.