Hi, the nightfall specific loot is not guaranteed. There is a certain drop rate for it. I believe I did about 50 prestige nightfalls before I got mine, so my chances of getting it were at 2% per nightfall run. These numbers will be different for every individual, most of my friends got theirs in less than 10 runs which means their chances were higher.I personally went for doing as many Prestige Nightfalls as possible within the shortest time, so I was having 8-9 min runs with a score of 20k-ish. It is all RNG based, so the people with most luck get it quicker. High score Nightfalls (110k-200k score) should be also increasing your chances to see a DFA at the end chest. Good luck Guardian!