How about a reverse objective? On World's Wake, reverse the triangle formation to 1-2-3-4. You start out with all crusaders unlocked, recruited and level 1. You fill the formation with the chosen 10. Every 20th area you lose a space in the formation and therefore a crusader. By the time you reach area 180 you're left with a single crusader to power through the remaining areas to your goal of 200.