There should be some kind of counter for victorious fights. Fighting the Dark Lord 50 times during the event for a guaranteed girl drop or something like that. Also I know it's a bit tricky to do, because of the resposive view page layout, but maybe there should be an ingame page with all event details listed + the number of remaining fights.

I think the most players would prefer a game mechanic that's equal for all players instead of trusting their own luck even when it takes days of grind.