Tower #4

Level 1, cost = 3000 crystals, yield = 3.05%

Level 2, cost = 4500 crystals, yield = 3.1%

Level 3, cost = 6750 crystals, yield = 3.13%

Level 4, cost = 10200 crystals, yield = 3.15%

Level 5, cost = 15300 crystals, yield = 3.19%

Level 6, cost = 22950 crystals, yield = 3.21%