Other info stuff

Reishi
A spirtual particle that makes all spirtual things. Reishi is in each and every Shinigami and Hollow. The Hueco Mundo and Soul Society is made completely out Reishi. This spirtual particle, also can be known as spiritrons, is invisble to almost all humans. Quincy's are the only humans that it is not invisble to. In fact, Quincy's use Reishi that the collect so they can use combat, this reishi group forms into a Reiryoku. A lot of Reishi seems to be in places where Nature is close. This spirtual particle can also be controlled freely so people can use a techinque called hoho, or Hirenkyraku for Quincy's.

Chain of Fate

The Chain of Fate is what binds souls to their living body. When the Chain of Fate is broken, an erosion will take place from the end of it after being broken. Once this happense a gradual process of hollow transformation takes place. A sign of being a step closer to becoming a hollow is when the soul with a broken Chain of Fate starts to feel hungry. The erosion of the last peice of the Chain of Fate is far more painful than that of the previous ones. (Last Erosion)

Encroachment

During Ichigo's training, he went through a particulalry lethal lesson called Shattered Shaft. He had to escape the shaf in time to gain his own Shinigami Powers, or elese he'd become a hollow