The Tower

Description
The Tower is a mysterious place something metaphysically complex, though it is perceived as a place by someone's mind when he sees or visits it. Its existense is a secret known by a handfull people as entering it (as well as leaving it in one piece), requires a great deal of magic and mind power.

Entering the Tower
So far, entering The Tower safely is limited to Shard holders, powerfull mages capable of dimensional traveling, demons, Gods and (perhaps) Anti-Shard holders. Other people who fall into any of these categories and somehow end up there lose their minds as they can't handle the experience. Only King Alonon has managed to "see" the Tower and remain (somewhat) sane. An other way of "seeing" the Tower by is being possessed by a Seed of Corruption but that is hazardous in both physical and mental level.

Inside the Tower
The Tower could be described as an infinite ladder that crosses the Demon Realm, Reality and the God Realm. That means that someone could use the Tower in order to traver between these Realms. It holds a really great amound of power as one can find Soul Shards as well as Anti-Shards in there. Also, any mortals who manage to survive demon attacks, while being there, become powerfull corrupted abominations.

Fan theory
Due to the dual nature of the Tower (God/Demon Realm, Shards, Anti-Shards) It could be speculated that there is a part of the Tower where Soul Shards are destroyed if placed there.