soulstones

lvl2 = you need 3 lvl1 stones = 1.590 gold
lvl3 = you need 3 lvl2 or 9 lvl1 stones = 4.770 gold
lvl4 = you need 3 lvl3 or 27 lvl1 stones = 14.310 gold
lvl5 = you need 4 lvl4 or108 lvl1 stones = 57.240 gold
lvl6 = you need 4 lvl5 or 432 lvl1 stones = 228.960 gold
lvl7 = you need 4 lvl6 or 1.728 lvl1 stones = 915.840 gold
lvl8 = you need 5 lvl7 or 8.640 lvl1 stones = 4.579.200 gold
lvl9 = you need 5 lvl8 or 43.200 lvl1 stones = 22.896.000 gold
lvl10 = you need 5 lvl9 or 216.000 lvl1 stones = 114.480.000 gold