Talk:Sortie/@comment-27776928-20160706035245/@comment-4448946-20160720190912

All rewards that have a check mark next to them after you obtain them are non-repeatable rewards, you can only get them once per sortie season. Once you get them  they will no longer drop for you and if the RNG choses them as your reward you get fusion cores instead.

Season 7 once you got all the Lens', Nezha and Dera Parts you have a 97.666% chance of a Fusion Core pack.

The percentages are correct Season 7 was just long and you did a lot of sorties.