Asmodeus

Asmodeus is a demon who appears in Gehennom. He is no trouble at all, provided you have decent AC and cold resistance.

Alternatively, you can pay Asmodeus instead of fighting him. He asks for a portion of your visible gold so it is best to hide most of it, for example in your bag of holding.

Asmodeus always drops a wand of cold and a wand of fire upon dying.