Brainweed
by Mike HarveyBrainweed (inspired by Brain Collector and Gelatinous Cube)
Brainweed vaguely resembles kelp: tall slimy stalks extending a hundred feet or more from the seabed, buoyed by pumpkin sized gas bladders. Unlike kelp, brainweed has no leaves, and exudes a thick slime. Brainweed preys on animal creatures such as fish or humanoids, which become entrapped by the stalks and engulfed in the slime, which digests them much like a gelatinous cube, but slowly. Because of this, the slimy stalks are festooned with partially digested bones and entrails, like some sort of ghoulish forest. But the brains of intelligent creatures are not digested, they are encapsulated in tough transparent pods and preserved. But for those brain pods the weed would be just another mindless lowlife, but the captured brains give it ever increasing intelligence and eventually spell ability. The spells are used to lure prey with illusions and charms.
Brainweed grows at very murky depths where little light penetrates, and the tall stalks make it even darker. Juvenile brainweed is unintelligent and lures creatures with organs that produce a dim greenish light. From outside it appears to be a patch of weird fungus with odd lights somewhere within, inviting further investigation. Unlucky creatures that swim into the patch are paralyzed when touching the slime (same as gelatinous cube) and engulfed. As brainweed becomes more intelligent and magical, the brain pods themselves start to glow with the same greenish phosphorescence. Juvenile brainweed has also been known to capture swimmers near the surface whose feet brush through it. :facepalm:
Brainweed can survive on fish but prefers intelligent prey and goes to great lengths to acquire it: it will charm victims and send them back with tales of sunken treasure; case massmorph on itself to appear as ordinary harmless kelp; animate zombies and skeletons from previous victims to use as kidnappers and guards; produce illusions of treasures or sunken ships or fantastical undersea cities... all to lure victims into its slimy trap. It actually does have real treasure: it cannot digest metal or minerals, so any possessions or magic items carried by victims fall to the seafloor. The deeper you go the darker it gets (making the glowing brains stand out in contrast), and the thicker the slime. Slime may be ten feet thick at the base of a mature patch, and at the bottom of the slime is its treasure.
Brainweed seems to reproduce by occasionally releasing polyps, not unlike anemones. The polyps float until they attach to some surface, preferring dark depths. Polyps produce a faint pinpoint of light to attract scavengers and bottom feeders: crabs, suckers, and so forth. The tiniest weeds sting like jellyfish but can't harm an adult human; a bit larger and they can cause 1-6 damage from the intensity of the sting, plus save vs Paralyzation at +4 or be stunned for 1-3 rounds from the pain and shock; a little larger and they can catch and kill humans, but the save is still at +2 until they reach a mature form.
Undersea races know all this and teach their children to avoid the hazardous polyps which might be found nearly anywhere; larger mature patches are noted and avoided, but as they become trickier and more subtle they are still able to catch wanderers who are not familiar with the local sea and have not been warned to avoid it.
Marine leviathans are completely immune to brainweed and seem to consider it a delicacy. Occasionally one will find a patch and devour it completely, serving as a natural check to proliferation. Intelligent brainweeds know about this and fear it, but also use it: they have been known to send charmed victims to settlements with reports that a patch has been eradicated and its treasures exposed...