I think there was a bug or exploit with the crystals so they were removed. There might be something under floor object or wall object or a defendable/destructible item that you could use.
http://tiny.cc/ArcaneDefenseItems
This is a bug, nothing more. Please put away the tin-foil hats, there's nothing sinister going on here.-Protea
http://tiny.cc/WhatBeatsADragon
Probably to prevent people from loading their arcs with the CoT's regeneration/recovery crystals.
I have noticed there were no crystals (object) in the selections. I may be wrong, but i swear i scrolled up and down over and over to find one. Anyway, i was looking for a specific crystal if it exists. It is called "Soul Crystal" from Ghost Widows story arc, but any crystal will do if it is not available. pls help!
here is a link from paragonwiki:
http://paragonwiki.com/wiki/File:Red...oulcrystal.jpg