Dysfunctional Citadel

As they went back up the stairs, Sunny couldn't help but think about what he had seen in the stone chamber at the root of the great pagoda. The circle of runes, the sublime crystal hovering in the middle of it… that had to be the core of Hope's tower, as well as of the whole island. The very heart of the Citadel.

But what was its purpose?

An easy conclusion would be that the divine soul shard was the energy source that powered the enchantments keeping the Ivory Island afloat. But that did not make any sense… the runes had been carved by the Demon of Desire herself, which meant that the enchantments had been created before her kingdom was destroyed.