By the way, SaberCherry, thanks for pointing out that it is a "relative" rather than an "absolute" decrease in events.
I will tell you, though...it seemed to be an absolute decrease in events when I played Ctis with order 3 and balanced luck. Almost no random events.
Your formula is probably right and mine probably wrong. I didn't get an increase since I didn't take unluck. I don't really miss those handfuls of gems.
