Psibuster
Description: a metal cube, typically carried in a cloth bag with straps. There is an obvious firing pin at the top that must be unlocked with a key before it can be removed. The lock is not particularly difficult to pick: the idea is more to keep the Psibuster from being accidentally activated. A Psibuster is generally set to ‘detonate’ when thrown against something hard, but can be primed to go off when any physically present psi actively uses a power within one yard of it.
It’s basically a satchel charge that can only be used against psionic targets. It does kind of affect non-psis, but not very strongly: anyone within its area of effect (1-yard sphere) when it goes off will feel briefly queasy, and possibly get a touch of vertigo. Those with some sort of natural psionic resistance will feel nothing at all.
But people who are psionic (very much including people using psychotronic technologies)? Hoo, boy. The effects start out with vomiting, loss of bladder/bowel control, and random muscle spasms. Anyone actively using a psionic ability at the time of detonation will likely be knocked out — possibly bleeding from the nose in the process — and God help a teleporter caught in the moment of transition, because the after-effects are rarely pretty. Mind gestalts and other shared psionic activities can get absolutely shredded in the sudden feedback loop. Psychotronic technologies fare no better: they invariably burn out, sometimes explosively. And so on.