I think it would be really cool to have to fight boss enemies when your tribe reaches certain experience points.
500 pts - A tribe of 5 fully armored barbarians
750 pts - Two Ogres
1000 pts - A Giant Snake
1500 pts - A Shade or Phantom
2000 pts - A Dragon
2500 pts - A Three Headed Super Dragon
You can hide in a castle, but the shade can pass through walls (because it's a spectre) and dragons can fly over them. They would spawn near you and keep chasing your tribe until you defeat them!
How fun would that be!! :)
Customer support service by UserEcho