In book 8 it said he saved a young scorpion in his bag of holding to dump in the well to be able to hunt more later. I've been thinking about this too. It say a core token and the war leader. I believe this is implying there is only one available. I was first thinking this wouldn't have meant Richter since Yoshi should have been able to make a more powerful war party. Later though, I came up with the supposition that Yoshi might have been kicked out of the war party when he was thrown back into the dungeon because you can't be in a war party in the dungeon?