The Pulsator (Mahistem) is a psionic Dreadhar, one of the Darukin that come through the Nexus Fractures, and it belongs to the Nousshars, the brood of Adaàr'Kabat, the Shatterer of Minds, who turns their spawns against thought and memory. Where many of that brood are content to watch and unsettle, the Pulsator lays a firm grip on the minds around it and can do them real harm.
I have pieced this entry together with rather less certainty than I would like. A Pulsator is too dangerous and too valuable to its brood to be cornered and penned for study, and I have never had one still and harmless in front of me. What I set down here comes from the Riftbreaker actions I joined, where one was present, and from the Sentinel scholars who have faced them far more often than I have.
Pulsator Physiology
The Pulsator is a lobed and folded mass of pale magenta flesh, wrinkled and convoluted over its whole surface, solid and thickset and clearly made to act. The body itself stands no higher than a grown soldier's knee, low and broad, light enough that one strong person could carry it off under an arm. A cluster of long, thick, dark purple tendrils sprawls out from beneath it. These tendrils are its limbs, and it hauls itself along on them at a fair pace, kept low and spread wide over the ground. They are strong enough to grip, to drag, and to knock a careless soldier off their feet.
Its front is crowded with eyes, a cluster of broad slit-pupilled eyes set deep among the folds, most of them large and turned mostly forward. This is the look of a creature that means to face what it deals with head-on, its gaze fixed forward on whatever stands before it. Below them sits a wide bony maw, lipless and crowded with small sharp teeth, the one part of the Pulsator plainly meant to wound. It will use that mouth if you press it hard enough, though it keeps biting for a last resort, and a creature this reliant on the mind holds its real strength elsewhere.
The Pulse Organ
The feature that sets the Pulsator apart, and the one that gave it its name, is a single long tendril that rises from the top of the body and curls up and over it, held high above the rest. It ends in a smooth, pale bulb, larger than a clenched fist and oddly out of keeping with the rough folds of the rest of the creature. I watched this organ closely on the one occasion I had the chance to. Before the creature strikes with its mind, the bulb swells and tightens and gives off a slow, visible pulse, two or three beats of it, and then the blow lands. If you ever see that bulb begin to throb, you have a breath, perhaps two, to do something about it.
The Pulse
The Pulsator's chief weapon is the psionic burst released by its bulb. The Pulsator throws out a wave of raw psychic force that strikes every mind within a stone's throw at the same instant. I have felt the edge of one of these waves, and the closest I can come to describing it is a sudden splitting pressure behind the eyes, a white shock of pain that empties the head of every thought for as long as it lasts. Those caught full in it buckle where they stand, some clutching their skulls, some dropping without a sound. The wave leaves the body whole and unmarked, since all the harm it does is done to the mind. But the damage it can cause to a mind can be so severe that it can batter a person to the ground and leave them of no use to anyone for a while.
Disguise and Compulsion
The pulse is the prime offensive weapon of a Pulsator, but it’s not the only tool at its disposal. Given a little time and a clear sight over its target’s mind, it can listen in on the surface of a person's thoughts and pick up what they fear, what they intend, and what they are about to do. It can press a suggestion into that mind so smoothly that the victim takes the idea for their own, and it can force a short, flat command that the body obeys before the will has any say in the matter, a single word's worth of compulsion, enough to make a sentry lower a weapon or unbar a door. I have watched a young Sentinel guard turn on the comrade beside them under that pull, certain for those few moments that they were doing the right thing.
The Pulsator can cloak itself as well, throwing the look of a harmless object or a low beast over its own bulk, though a creature of this size and sprawl is hard to hide. A Pulsator that has time will use all of this together. It hides itself, reads the minds around it, steers one or two of them with a suggestion or a command, and keeps its pulse in reserve for the moment its disguise breaks and it needs to flee in a hurry.
Where It Appears
You will meet a Pulsator only where a Nousshar incursion has already taken root, well behind the first scouts, at a held Nexus Fracture or in a settlement the brood has begun to work through. It keeps to the middle of whatever force it travels with, screened by lesser spawn and by its own disguise, since it is too useful to risk at the front and too dangerous to leave idle at the back. When a Fracture is sealed and its brood broken, a stray Pulsator stays a serious problem for as long as it lasts, since it can still hide, still read the people hunting it, and still turn one of them against the rest before it is finally run down.
How to Deal With One
If you have any say in the matter, deal with a Pulsator at range and deal with it quickly. The pulse and the grip both need the creature to keep you near and in sight for a little while, so the worst thing you can do is stand close and give it that time. Watch the raised bulb above all else, since the swell and throb of it is the one clear warning you will get before a pulse, and a heartbeat's notice is enough to throw yourself flat or behind cover and take the lighter edge of the wave in place of its full weight.
The hardest part of facing a Pulsator is the harm it can turn back on your own side, so set one rule for the company before you go in. If one of your own turns on the rest for no reason, a Pulsator might have hold of them. The creature behind it gives little trouble once you close the distance, since it keeps almost nothing to defend itself with at arm's reach, and the whole struggle is in holding enough of your wits through the pulse and the pull to reach it at all.