I really like the idea of the Psi Caltrops/Psi slow-zone but I personally think it should only proc once per enemy per cast. TM is already packed to the brim with some of the most potent and unique utility effects in the game. On a tangent, we already have ice barrier block zone(metathermics) and force wall(psychokinesis) in addition to caltrops and traps slowdown as well as others too. I know psi-slot equip limits and build limits makes my point a little moot overall. I think that the psi-temporal attacker with orienting around buying time for the super Temporal Distortion delayed attack-stack to explode could use a spell like this for good use without being remotely op imo.
I'd the spell something like: Temporal Glue: creates an invisible slow-zone(size slightly smaller than caltrop area) that slows everything except yourself by 20 movement points once per turn if they touch it.
I'd also like it if Temporal Rewind could be used on enemies to undo health-hypos and self-buffs used temporarily and also move them back their move tiles again(doesn't undo their attacks, only undoes last action'ed turn). The move tiles lost should not be given back as it makes no sense if they move again..? I think..? I hope.. (edit... unless you can use it on yourself to gain a ton of bonus mp on turn 1 as you initiate combat...? yea that sounds broken since same school also has Psycho-temporal contraction, and steps on its toes a bit at that too..)
Also, Temporal Distortion.. I personally think having it's Continuum Ripple feat buffed wouldn't be a bad idea.