Talk:FAQ/@comment-131.104.23.4-20150319143155/@comment-26093926-20150321013440

You'll have plenty more chances of fighting as you play along and there's no need to restart your game. They appear more than once as long as you keep repeating runs in maps that have the black/purple icon, but you'll have to rely on RNG roll you an encounter. Also, I think that drop rate is not affected by level of your team or enemy team's but the rank you clear them with (S, A, B, C...).