It should be 100% imo, Not only is it hard(even for the richest vets) to reach it but you can only do it once a week per char. If even iRO rates are 90% then why are we making it 50% ? Satan Morroc drops all of its stuff 100% of the times and its much much easier to kill with a fixed spawn and a memoable map. I could understand the 50% rates if the time limit was customized to 1 day instead of 7 or something.