Combat in the New Psi, or How I Learned To Stop Worrying And Love Metathermics
Metathermics is currently the best school of psi to play if you want to get through combats with the greatest psi efficiency. You only need 3 abilities to make this work (though I'd recommend 4), and in the entire game, there are only five fights that are highly resistant to this school (counting all native invasions as one, for purposes of grouping, even though certainly depending on how you play there may be several invasions). Psychokinesis and Thought Control are viable primaries as well. Temporal Manipulation, while technically possible, is not an ideal choice as a primary due largely to the need to cast many spells quickly to get the most out of its main damage spell.
ThermoD was "nerfed" in a most curious way, this patch. It does less damage, but its damage mechanism wasn't changed, so it still scales out of control if you can group up enemies. It also requires fewer Action Points to use, making it reasonable for use without Premeditation. This leads to an inescapable conclusion.
Innervate Cryokinesis, Thermodynamic Destabilization, Pyrokinesis, and Pyrokinetic Stream. Find a chokepoint, and lay down as many bear traps as necessary to make yourself safe. Now, make some noise; you might use a grenade, or perhaps you'd like to carry around a firearm. In any event, what you want is to gather enemies up, which the AI will gladly do. At this point, you should
Place ThermoD on the highest health enemy you can easily kill and which is near the middle of the group (5-10 AP, 30 base psi cost)
Cast Cryokinesis on the target most likely to survive the explosion (7-10AP with unspecced Thermodynamicity, 15 base psi cost)
Throw a grenade (15 AP)
and if necessary,
Premeditate a Pyrokinesis (0 AP, 20 base psi cost with unspecced Premeditation)
After the explosion, as needed
Cast Cryokinesis (7-10AP, 15 base psi) on any stubborn survivors and if you like
Throw another grenade, or
Cast Pyrokinetic Stream.
Congratulations! You have mastered New Psi!
If you would prefer a more classic Psychosis approach, then Innervate Cryokinetic Orb, ThermoD, Cryokinesis, and Pyrokinesis, and after you've acquired a group as you prefer,
Premeditate + Psionic Mania + Cryokinetic Orb (0 AP, 30 base psi cost) and if anything survives
Cast Thermodynamic Destabilization (5 AP with unspecced Thermodynamicity, 36 base cost) and either
Throw a grenade (15 AP) or
Cast Cryokinesis (10 AP w/unspecced Thermodynamicity, 17 base cost) on a secondary target if needed, then end with
Pyrokinesis (17 AP, 48 base cost) or
Throw a grenade.
Congratulations! You have mastered New Psi!
In the event you're dealing with highly flame-resistant enemies, I would suggest:
If dealing with robots, throw a grenade (EMP, plasma, or both)
If dealing with Bladelings like during the Beast fight, then after you've laid down a lot of traps, you should throw grenades down into the kill zone - gas grenades and HE are a great combo, and as the gas debuff ticks on them, even incendiary grenades will do damage.
If dealing with heavily armored enemies, then you should throw a grenade or two to augment your ThermoD damage.
Of course, you don't need to use Metathermics at all. Other builds will also be viable.
For Psychokinesis builds, you'll be working with a lot of stuns. Your psi will do very heavy point damage but not much AoE damage, so you should probably throw some grenades to clear up the weaker enemies while you Innervate and use Proxy + Punch/Implosion and Electrokinesis + Electro Trap. I'd recommend something like:
Lay down traps to create a chokepoint, and make some noise. When the enemy comes running,
TK Proxy (5-10AP, 15 base cost)
Force Punch on a hard target (5-10 AP, 50 base psi cost) then
Premeditate an Electrokinesis (0 AP, 18 base psi cost) to get an additional stun. Then you should probably
Throw a grenade (15 AP) to kill off weaker enemies, and if necessary
Throw another grenade to incapacitate any survivors. At this point you've probably burned through most of your psi pool, so probably take a booster and end the turn. On the following turn, clean up by
Moving the Proxy (5-10AP, 15 base cost) and/or
Electrokinesis (25-30AP, 35 base psi cost). If there are still survivors, you may want to escape LoS so that next turn, thanks to Grenadier, you can
Throw a grenade to clean up what's left.
Congratulations! You have mastered New Psi!
Similarly, Thought Control is still quite viable. You'll only need to Innervate two abilities: Enrage and Neural Overload. Anything else will be QoL. For easier fights against groups of organics, you may want to just
Lay down as many traps as needed to create a chokepoint, make some noise, and
Premed + LoC + (Psionic Mania if Psychosis +)Neural Overload (0 AP, 7 (9) base psi cost) then if anything survives,
Throw a grenade (15AP).
For harder fights against living targets, it might be wise to
Create chokepoint as before,
Premed + LoC + Enrage (0 AP, 25/30 base psi cost) and then
Throw a grenade (15AP) to get some damage down. Keep out of LOS, so you aren't targeted by the enraged enemies, and when enrage drops,
Throw a grenade (15AP) thanks to Grenadier, and if needed,
Throw another grenade (15AP) and/or
Cast Neural Overload (13/18 base AP, 15/18 base psi cost)
Congratulations! You have mastered New Psi!
Even Temporal Manipulation should be possible on any difficulty, though it'll be a good bit more expensive in inhalers and psi boosters over the course of a game. Innervate Temporal Distortion and Entropic Recurrence, as well as Limited Temporal Increment and Psychotemporal Contraction. TD really requires that it be cast a lot of times in quick succession, and preferably on large groups to get the best effect from Continuum Ripple, so Tranquility is really the only good choice for a TM primary build. Probably the most efficient TM cycle would be:
Lay down as many traps as necessary to create a safe chokepoint. Make some noise to gather a group, then
Throw a grenade (15AP) to put some damage on the enemy then
Throw another grenade (15AP) to incapacitate them if organic or stun if robotic. End the turn.
Stack as many TDs as possible on one target and end the turn.
Stack as many TDs as possible on the same target (or another, if you're doing weak group cleanup and would rather Ripple than use more grenades) and get out of LoS/get your shield up. On the following turn,
Throw a grenade (15AP) and, if you've got a strong enemy causing you trouble,
Entropic Recurrence (5AP, 15 base psi cost) to echo that heavy grenade damage. From here on out it's just a matter of playing keep away until your TDs / ER ticks wear them down.
Congratulations! You have mastered New Psi!
button is so hard and is only done when you are frustrated. 
this has to happened when the fucking drag n drop finally spawns 
<- Styg
From temporal it was distortion and limited temporal increment. I actually forgot what else was on that psi bar.
