For every :
5orbs = 1chest
you need a total of 200chest to have the final reward
so 200chests x 5orbs = 1000orbs needed
When its eclipse go to OUTER WALL OF SERDIN and finish the run
1run = 5orbs = 1chest
so, 1000orbs / 5orbsperrun = 200runs...
It means that you need a total of 200runs in OUTERWALL to get the reward