The way the skill trees are built for the psyker and the ogryn means they cannot combo any combination of aura, blitz and ability, the core trio for each class. Where the zealot and veteran can do this.
For the psyker ‘prescience’ locks out ‘venting shriek’ and ‘kinetic presence’ locks out ‘scriers gaze’. For the ogryn ‘indomitable’ blocks ‘coward culling’ and ‘point blank barrage’ locks ‘bonebreakers aura’.
In contrast the Zealot and Veteran can combo any aura, ability and blitz at level 30 giving them more build flexibility by using the lateral sections of their skill trees. Given that every class is supposed to have balance and parity in build complexity it feels odd that those two classes have more builds than the others/the former group has less.
Likewise this puts ‘seers presence’ and ‘loyal protector’ in a special place for the ogryn and psyker where it has more build options and potentially more viability in the long term as builds become better explored. This affects internal complexity/balance.
There is also no clear reason (please correct me if I am wrong) why those cannot be combo-ed from a game balance perspective.
Ultimately this results in zealot and veteran having 27 core builds and psyker and ogryn having 21 core builds. I.e. 78% of the complexity, (if you include keystones this percentage would be maintained).
I really do love the skill trees and the blitz, aura and ability concepts. It revolutionizes the game but this seems like a design oversight that psyker and ogryn are more limited in builds than the other classes.