Around 1000 C for pretty much any metal to glow bright red
I've always been partial to chains. I love the how cold they are. A promise of what's to come. Even as I write this I have a face in my head. Chained around the feet, hung upside down. Left to rot a day in a dark, damp abandoned factory, some food factory, one with huge industrial mixing bowls. Filled with boiling water the day of the meal. The chains heated until they grow bright red, illuminating my face. Then white hot, illuminating all of the mirrors set up around, not giving a glimpse of what's beyond me, you and and the little time you have left. The heat has spread throughout the chain onto your skin, as it burns, and vaporizes the oils and hairs on it, as the metal fuses to your skin, as you scream. Until the heat and weight snaps the torturous piece of metal keeping you from boiling alive. And you fall. And I eat for another day.
cheers
-I
this question is so broad.
you can shoot someone, cut, beat, throw out of a window/bridge, drown him, poison him, throw him to dogs/other predators, frame him to some shady people, send other people after him, bleed him to death, suffocate him, etc.
I'd prefer the fastest, most convenient way that can be easily hidden or framed on someone/something else.
but i'd rather not kill anyone, thats counter productive in most cases and a waste of human resource.
now if its a female and i do it for fun, thats a whole different story. a story for another time.