Deva brought Raven inside a huge tower that was taller than anything he had ever seen in his life before. It was tall and black and made out of a strange stone that resembled marble in look—however, when he touched the stone, it started to absorb his anima!
"Careful darling... those stones are designed to endure the low mana and desolate world of Hell and absorb magic, mana and aura at alarming rates."
I see... it's a special stone, but this could be used to...
"These stones were found by my mother in the deep depths of Hell where strange, monstrous beasts linger made of pure black essence able to corrode and devour anything they meet."
Those creatures from Emily and Nene's dungeon!?
"We used them at first to stop monsters attacking our settlements as it would devour their aura and mana, but then we realised a new usage and built this tower at the cost of hundreds, almost thousands of Hell citizens... as the draining effect is deadly."