69 CROSSROADS. The floor of this room is different from the rest of the level. The central path is a cross of sorts, connecting all four exits. The floor of the this path consists of tiles colored in gray and blue. Upon treading on these colored tiles, the character will experience a shock for 2d4 damage (save vs paralyzation for half damage, metal armor saves at -4 if no boots/insulation). The harmless remainder of the room is tiled in white and burgundy.
Once discovered, this trap should be fairly able to avoid in the future, except there is a 25% chance that the charged and uncharged portions of the floor will exchange each time the room is re-visited.