yeah...first question I'd have had at the end there is does it only work if he dies...there are so many creative things you can do to a person without actually killing them, and that list is certain to be much longer and contain even more thoroughly satisfying options in a world of magic
@gagegageha as a general rule of thumb, such enchantments tend to work off intent rather than time or distance, most likely if you take actions to ensure someone's death, provided you attack them directly at any point or depending on the enchantment maybe even if you don't, it will still target you...that said, it might be possible to be more roundabout in killing if you truly need to have him die, by say, making someone cut off his limbs and manhood, cut out his tongue, healing him enough he absolutely wont die from what they did, then leave him somewhere someone else is highly likely to kill him while he's so weakened, but even then it'd be risky especially if it's the latter type...plus in my opinion, if you have the means to do all that, it's a waste to do it anyways...why allow him the mercy of a swift but painful demise demise at someone else's hands when you can offer him a greatly extended agony lasting long long past the point where he begs for death?
@endo54 it's a passive enchanted gear effect not an active spell