User blog comment:Xilinoc/Ch. 604 - REVITALIZE/@comment-24153155-20141106205952/@comment-24913480-20141106221155

Interesting theory with the nature of this "power", especially the take on higher dimensions. We know the power transfer didn't involve reishi (stated by Haschwalth) and I don't think it was just simple reiatsu (the cage would probably block it) so this "power" could revolve around some extra level of reality that has not yet been refered to (and it could connect to the Soul King: transcendence and all that), somewhat like dark energy and dark matter.

Could also be refering to the concept of "power" itself: http://powerlisting.wikia.com/wiki/Concept_Empowerment

but without having an actual affinity.

Both ideas would explain why the tree cage couldn't block the power: the very existential nature of the cage (being of a lesser/lower dimension) prevented it from interfering with an element of an higher dimension.