Simple, really. Surprised nothing like this has happened before. Multiple party leaders with open parties in one tile. It happened on accident when two people were trying to race to pick me up from Abonia, and thanks to them, I discovred it, played around with it a bit to try and find as much detail as I could, and then Dolph did his thing. Also, when your parties get into a fight, you get all the exp and gold from each fight. Dolph was in 13 parties, so he got 13x the exp and gold, even though he really only acted out one battle.