Obtained from Tavid Dennant in Guild Lobby by saying "molting". This item can then be used in the same manner as a Temporal Molting Cell for upgrading your SOD gear proving you have the lower version already made and the higher level essence. This is a great way to upgrade your armor from lucky loots without gaining access to higher levels of the void.
** Note - your toon will be restricted to 16 of these or a combination of these and other items he offers when you hail him.