Today's RNG are [i]good enough[/i] to produce reasonably random distributions over short runs (less than 10,000 iterations). Basic sample theory tells us that, for a yes/no type question (for example, do you receive an exotic as a reward for Roc?) sample margin of error for an n of 200 would be around 7% (pushing the sample to n= 500 would push it closer to the traditional +/- 5%). Thus, back of the matchbook estimates of exotic drop probability should be somewhere between 1:200 and 1:50. (Note: I'm not commenting on whether the OP has been able to actually do 200 Roc runs. Nor am I considering that the loot drop tables may have changed during the period the OP was running his tests, thereby invalidating everything. Also, yes, I know I skipped several important steps in my estimates, but we're not curing cancer here and I don't feel the need to worry about 5 decimal point of accuracy regarding the question of whether you, particularly, will experience a given result.)