Word of advise save up your primos for good 5 stars charaters later on the challenges get harder and harder especially when your world level levels up its harder but better rewards also farm chests
Also once you get a bit board of main mission try side quests for the rewards also always farm rare ascension items there's a certain amount you get everyday once you claim all you need to wait the next day for said materials to respawn or visit another's world to farm their items
Word of advise save up your primos for good 5 stars charaters later on the challenges get harder and harder especially when your world level levels up its harder but better rewards also farm chests
Also once you get a bit board of main mission try side quests for the rewards also always farm rare ascension items there's a certain amount you get everyday once you claim all you need to wait the next day for said materials to respawn or visit another's world to farm their items