I love the challenges to get food, XP and gold. But I must say they are quite difficult to navigate. I have 350 friends and the scrolling is crazy.
What about making something fun like you did with the dragon book. Create different arenas for different levels of players. For ex. One arena could be for players in levels 1-20. Another arena for players in levels 20-30 one for players in level 40-50, etc. it would also be great if the arena would save the dragons that we want to use in challenges like it saves them in the league battles.