I like this suggestion
level 10: 3 cubelets, 200 eggwars coins , 200 skywars coins. (I am going to explain later what coins should be)
level 11: 3 cubelets, 250 eggwars coins, 250 skywars coins.
level 20: 5 cubelets, 300 eggwars coins, 300 skywars coins.
level 50: 15 cubelets, 1500 eggwars...