Prestige is 360 (plus whatever handicap you add). (Destiny)

by CruelLEGACEY , Toronto, Monday, August 20, 2018, 14:33 (2364 days ago) @ Burchie

Probably not gonna be able to help at 341, unfortunately. :( (To ensure hitting the bonus threshold, you need a handicap of around 25 - meaning you want characters at 385 or above.

Correct me if I am wrong, but to get the upgrade from rare to legendary (not Masterworks) you just need to complete any nightfall. Not necessarily prestige and no bonus points required. I think the recommended light level is 270, but being my first nightfall I don’t really know what to expect.

^This is correct.