The magicka aid passive in the support skill line is not currently working with purge. Slotting purge does not increase mag recovery like it is supposed to.
The passive is working with other support skills like barrier, siege shield and guard. Have tested this with multiple people on PC NA and EU. I have also tested it with un-morphed purge and efficient purge and at rank one and two of the passive and it never gives the mag recovery bonus.