Complex sentence: The last room is decorated in black and is illuminated by a scarlet light- "a deep blood color": because of this chilling pair of colors, very few guests are brave enough to venture into the seventh room.
Split into simpler sentences: The last room is decorated in black and is illuminated by a scarlet light, "a deep blood color". Because of this chilling pairing of colors, very few guests are brave enough to venture into the seventh room.