Jason has had a hard time commenting, and spent the time to really help address his ideas for how to use Wyrdvane Psykers on the tabletop. Its right up my alley, and I appreciate all the comments we have had to get a firm grasp on the unit. Jason sent in this email and since he was not able to comment, I thought I would share it.
Personally, just like some readers have suggested, my psykers may just be reserved for Grey Knights or Inquisition retinues.
Jason has given permission to use his name and to post up his comments.
via Jason Collins on Faeit 212
In any case as a long time competitive guard player, I have to address this issue of psyker battle squads and people not understanding their efficiency IMO.
Psyker battle squads are good.. Because it allows you to position your divination at a different spot on the board.
Usually your primaris will be moving up in a blob. A psyker battle squad can comfortably take prescience and twinlink your artillery, your Russ units, etc, while your blob and primaris psykers don't have to maintain a 12 inch range to these units. The same with inquisitors. The primaris and the inq are 50+ pts minimum, the psb is 60 pts for the privilege.
Secondly, divination isn't a great psyker domain because the primaris is good.. The primaris being prescience makes it solid/reliable in letting you build your list around it. It's a great domain because other powers are pretty awesome.
When my psyker battle squads have prescience, my primaris don't have to swap for it all the time.. If I roll up powers I like, maybe a counter attack/full bs blob is cool? Maybe the blob ignoring cover (2nd power) + using the tank hunter order at the same time is great with twinlinked lascannons.. Maybe misfortune, or 4+ invuln blob, etc. All these powers you would end up swapping out for prescience - even though things like misfortune you want moving up in the field to constantly use.
Psb serve the roll to twinlink your army and stay out of danger. Inquisitors and primaris psykers walk up with your blob and will usually keep their more offensive options.
Just my two cents!