I'm curious about this as well. As far as I know (unless I'm mistaken) you can't get ascension on Ragnarok either, which means you can't actually reach the levels that Pyria will allow you to passive tame them at all... I'm a little confused on how exactly this is meant to work.

to unlock the engrams you need to kill the world bosses. from their you will have to find which one of the auras you can make

You will need to defeat either a Colossus or a Dark Mana Reaper Empress. To find them, just literally go into the most dangerous locations on your chosen map. They'll most likely spawn there.