She still believed that the chief was her only enemy.
Until an arrow imbued with brutal magical energy came flying down the hall towards her. “...!”
It came from a total blind spot. Without the keen sense she had acquired to run in the dark,
she would not have even noticed she had been attacked until it struck her. Picking up the disturbance of nearby magical energy and the faint creak of a bow being drawn, she realized she was being targeted.
The woman Assassin twisted, flexing her joints farther than seemed humanly possible, and evaded the arrow that had been closing in on her heart. It flew straight on down the corridor, and struck what was — from the shooter’s perspective — the opposite wall.
The impact wrought incredible destruction. The wall burst apart. The room beyond peeked through a hole bored clean through the reinforced concrete.
She did not know how it had destroyed the wall. All she knew for certain was... that the strike had been powerful enough to bring down any human, and possibly even an average Heroic Spirit.

Fate/Strange Fake: Volume 2, Chapter 3 ("Day 1, Early Dawn")