You're much better off with going a single Psi discipline now.
You can go multi, but for the first half of the game you might find it a bit too slow as you have to swap skills and drink mana potions .
So I guess Psi is going to keep on that kind of directions :/
Played a psychosis build from start to finish, here's my take from a psychosis perspective:
1) Old time quad school is just a bad option now due to vastly increased psi cost. The optimal way to play is to take Temporal (stop at 70 base skill) + one other school early ~ mid game. I went Meta because it's a better fit than Psychokinesis for psychosis - spam-able cryokinesis sniping and Cryokinetic Orb crowd control. Once you have Psycho-neural flexibility tri school is now an option. I went with Thought control so my build have two modes: Meta for frontal assault and Thought for silent assassination.
2) Short answer, yes. Long answer, yes but not just for PTC because Stasis is a huge deal. It's a defensive + offensive tool in one. If you are not confident you could save it as a reliable panic button, LTI + Stasis = reset cool down and second chance at victory. I used it more as an offensive tool -> adrenaline + PTC, Stasis to extend the buffed AP for one more turn for maximum firepower. This is especially important since Force Field is now unreliable. I personally high recommend all pure psi build take 70 base Temporal. You can invest more to reduce the chance of PTC debuff to a minimum of 30% chance but I don't think it's worth it. On dominating difficulty you are doing something wrong if you can't end a fight within 1 ~ 3 turns. This is another reason for my assassination mode - thin out the crowd to guarantee all fights end within 1 ~ 3 turns.
3) Pure psi with no crafting is just objectively bad. School specific psi headbands are vital and made a night and day difference in damage output. If you don't craft as a psi, the whole game sucks and DC sucks even more.
1. kinda surprised you didnt go Psychokinesis for the good ol' 1-shot Mania setup. Is there any buff on Metathermics to handle robots? I remembered Psychokinesis is a staple for psi build mainly for dealing with robots.
2. yeah stasis is nice, but I usually just use it for cheese. lure on tight corner -> bear trap, shoot em. if its not dead, stasis -> quick tinkering trap -> pretty much dead anything.
3. I totally forgot about crafted psi headbands.
so I guess other build doesn't get impacted at all? stuff like melee, cutthroat rogue, crossbow, the SMG and AK, etc