The tower was constructed primarily of Moonlight Crystal Soul Ore, supplemented by a vast quantity of precious mineral materials.
At the very heart of the tower, what maintained its operation were Top Grade Spirit Stones.
One should know, a single Top Grade Spirit Stone could be exchanged for ten Mid-grade Spirit Stones, and one Mid-grade Spirit Stone was worth over a hundred Low Grade Spirit Stones.
In other words, one Top Grade Spirit Stone could be exchanged for over a thousand Low Grade Spirit Stones.
The mere cost to build such an Obsidian Tower was an astronomical figure that even Su Jie dared not contemplate.
The three towers were arrayed in a character "品" shape, forming the Mountain Protection Array that defended the entirety of Ghost Ridge Palace.
Now, in a state of war, the Mountain Protection Array was operating at full strength, and the maintenance costs alone were swallowing up untold numbers of Top Grade Spirit Stones each day.
