Hello, I am new to OPR an this forum. I am playing Tabletop for some decades now and i enjoy the OPR very much and immediately patron it.
Yesterday I played with a friend for the first time GF: 1500 Orcs against 1500 Rebels with a Titan Lord. Of course the Orcs won, because they seized the mission targets. While playing I buffed my Titan Lord Crusader with Psycher from the Rebels. I casted "Foresight" on my Crusader, because in my mixed army he was a friendly unit and so he hit on 2+.
It seemed a little bit OP, so is it ok to buff a unit in a competative game from the primary army with a pyscher from the secondary army?
Yep. There is no penalty for blending different army books. It's easy to abuse (by taking units from other armies to cover up your army's weak points), but hey, so is the points calculator. Grimdark Future is one of those games where you can easily play like an asshole, and it's up to you to be sporting and fair.
I wouldn't worry about using a Psychic to boost your titan though. I mean, if it was really "overpowered" then, you know, why did you lose? Hard to argue that a model that got tabled is OP.