You supposedly have a better chance the higher your score, but in the time it would take to try and get the highest score you can in prestige, you could just speedrun normal. It's all just random. I've only gotten one Nightfall specific loot drop so far, and it was on a normal run with a low score.
English
-
this is only the second one ive ever gone before, i went for duty bound (savathuns song) and got that after 4 prestiges, this one isnt being as nice.