The Concierge is the first boss you will able to face. It is located on "The Bridge".
He does some melee damage and sometimes burns the floor to both sides.
It is hard the first but since you will gathering stuff and getting better stats will be easier.
One recommendation will be to use Wolf Traps to keep it quiet (so you can slay him) and also the artifacts that shoot stuff, so it will be busy battling those and meanwhile you will be able to do some attacks. Also recommended are some of the bows that shoot two or three arrows at once, so you will keep your distance.