Hill was no fool; how could he possibly use ordinary crystal walls in the Magic Tower, where the defensive power was so strong.
He was aware that since this world had been modeled after Ferun, there would certainly be magic-breaking weapons, albeit few, they would certainly exist.
Hill wouldn't feel at ease just because there was a Defensive Magic Array in place.
Even the sturdiest crystal could not possess the defensive power of obsidian.
The crystal windows of the Magic Tower were actually thick slabs made with crystal flower threads from Hill's family heritage, pressed and woven internally. These were obtained during his first interaction with Aurelio, the Earth Crystals.
They were more valuable than obsidian; even mithril ore of the same size wasn't as valuable as these windows.
When he departed from this world later, Hill would definitely take the entire large window with him and replace the vacated spots with obsidian again.
