I normally use 2 arrow rush to kill sponge + chair on floor 1. Haven't touch floor 2 and 4 yet. For monster in floor 3, i use arrow rush/dragon storm against David to 1hko. For Darcy and Herb shell that require 3 arrow rush, i use raion + scorching earth to aoe them as well as dragon storm/phoenix rising/incinerate to 1hko them. I have no trouble killing them, however, my survival rate is too low since i have no good hp shield. My high lk stat keeps monsters from hitting me but doesn't help against guard break.
Well, challenge is fine but I don't like dying very much.