Psyker can keep casting at 100% peril forever except with Inferno staff and Surge staff charged attack. Other staff attacks, weapon specials and force sword push attacks do not cause you to overload
The new overheat debugging code that was added is also spamming your log file with a lot of debug info every time you attack at 100% peril, possibly causing stuttering on some systems. But obviously that will be resolved once the root cause is addressed.
Have tested it with Voidblast staff, can’t overload both with its primary and secondary too. I think it’s the very last patch that caused it, because I played the game a few days ago with this character, and were overloading just fine
Plasma Gun on Vet doesn’t overload either right now, you can keep firing charged shots, uncharged shots will still do the small cooldown of heat before firing again.