A Prism Trap is a weapon and defence employed by the Defence Council to imprison immortal threats, more properly called an Etherium Crystallis. They appear as glowing, hovering crystals of various size. Oestenkeep has many Prism Traps around the headquarters of smaller sizes - Lord Dayblade also had one in his possession.

While the method of creation of Prism Traps is currently unknown, they can get physically damaged over time, such as the one within the Holding. With Knight Aedophon’s aid, O.P.E.R.A. helped restore this crystal, which involved the manipulation of ethereal chains.