A D&D party might encounter a hag after investigating a case of missing babies or afterdiscovering a town that has been torn apart by gossip, false accusations, or even nightmares.A solitary green hag or sea hag can be the primary villain for a 1st- or 2nd-level adventure. The tasks include running, jumping, climbing and flying. Can you build the ultimate creature that is good at all of the tasks? Some scientists believe that Trichoplax, with its stripped-down body plan and easy-to-manipulate genome, could be a useful model organism for medical researchers. It’s especially intriguing because it breaks the rules that most lab animals follow: Unlike mice or fruit flies, Trichoplax has an indefinite life span, rapidly heals, and never—so far as scientists can tell—develops cancer. “We’re always trying to figure out what the rules are,” says Billie Swalla, a biologist at the University of Washington who studies regeneration in weird animals like acorn worms, which can regrow their heads. Studying rule breakers like Trichoplax, which can tear themselves apart and heal in minutes, could yield insights into the treatment of human injuries like damaged spinal cords, she says. Hags can really shine — er, glower — in combat. A sea hag’s Death Glare is terrifyingly powerful against low-level adventurers. It forces a frightenedcreature to make a DC 11 Wisdom saving throw or drop to 0 hit points on the spot. Prakash hands it to staff scientist Hazel Soto Montoya, who puts it in the Igloo cooler with reddish seawater she has filled at the marina. Soto Montoya is currently studying the symbiotic bacteria that live in Trichoplax’s body, so she wants to re-create the ecological milieu in which they found it, red tide and all.

The test took place in one of Prakash’s recent inventions, a Ferris wheel–inspired contraption he calls the Gravity Machine. Composed of a thin plastic wheel full of water, the Gravity Machine rotates vertically in front of a powerful microscope, acting as an aquatic treadmill for microorganisms. Even in the narrow disk, which is less than half an inch wide, Trichoplax is so small that finding it with the naked eye is like searching for a dust mote in a gymnasium. I n Prakash’s lab, located in the leafy bioengineering quad at Stanford University, he and his graduate students, postdocs, and lab technicians are less concerned with figuring out where Trichoplax fits into the story of animal evolution than how it manages to live such a full life—creeping along the ocean floor, sensing its surroundings, eating algae—with such minimal equipment. “Where does behavior come from in a system that doesn’t have neurons?” he asks. He’s also interested in the shape-shifting animal’s basic physical properties: “Is it a liquid? Is it a solid? Is it something in the middle?” When the team leaves for the lab, I retreat to my dorm room at the Monterey hostel, defeated. I am not hardcore enough to hunt wild Trichoplax, I think. I take a nap. At 11:32 p.m., my phone lights up. It’s a video text showing Zhong and Soto Montoya huddled around the microscope, looking buoyant. Zhong has found a Trichoplax. “That’s it, 110 percent,” Prakash says. “It’s beautiful, beautiful!” On a computer screen that shows the display from the microscope, Trichoplax looks like a glowing, pulsing orb surrounded by cosmic protoplasm. Soto Montoya finds a second, bigger animal. They sign off and keep scanning each slide, one by one, until 4 a.m.There’s much more to learn about Trichoplax’s movements, however, Smith notes. The molecules that cause the animal’s cilia to pause work far too slowly to control Trichoplax’s fastest movements, she says. “If you watch movies of the animal gliding on its cilia, you see that the animal can change directions really rapidly, within seconds or less than seconds.” A lthough he’s one of the youngest scientists to fall for Trichoplax, Prakash is far from the first. The weakness for the amoeba-like creature often begins unexpectedly, when it squirms into a researcher’s field of view. The German zoologist Franz Eilhard Schulze, who discovered the animal, spotted it as it crept along the interior of a saltwater aquarium meant for other species. Smith saw her first Trichoplax when it glided across her microscope slide while she was examining some sea sponges. Please be awarethat this is more of a sandbox simulator demonstrating basic machine learningthan a real game.There are no achievements or player rewards. Even if a creature of yours reaches 100% fitness, you don't win anything except for (hopefully) lots of excitement and joy. Mistresses of misery, hags harp on primal fears and covet misfortune. The flavor of anguish they strive to create depends on the type of hag: An iconic faerie, pixies appear as tiny elves with delicatewings. They’re as curious as they are shy.A pinch of their dust can grant the power of flight to friends or confuse foes. Often hunted by mages for their dust, pixies rarely reveal themselves.

Later that morning, I reconvene with the team. Prakash’s cold has gotten worse, and Soto Montoya and Zhong are swaying with exhaustion. Still, they sit down, pull the remaining slides out of the seawater bath, and start looking for more animals.

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One thing Trichoplax cannot do, Prakash recently discovered, is swim. Some scientists say it can swim—including Pearse, who says she’s seen it. Others say it can’t. In a nod to the swimmer-versus-crawler debate of the 19th century, Prakash decided to give Trichoplax a swim test. In my opinion, fey creatures are usually either really, really, REALLY evil or pretty much just temperamental pranksters. They also are often portrayed as very elemental creatures, so pretty much just look at a regular type of Fey you might find in a specific situation and change as much as possible as far as possible and make a story to go along with it. Ultimately, Prakash hopes to understand how Trichoplax can survive the violent forces of its own mutinous body—as well as harsh environments like the rugged California coast, where a six-foot wave can pummel tiny ocean creatures with the force that a 1,000-mph wind would have on a human being.

Dungeon Masterscan use the boggle for either a fun side adventure or as a way to introduce the party to larger plot points. A boggle could steal an object from the party out of a desire to cause mischief and lead them on a slippery chase through a busy city. A group of bogglescould play a hilarious game of keep-away, creating Dimensional Rifts to pass a stolen item amongst themselves and filling tight corridors with slippery oil. Smith and her colleagues have found a series of evenly spaced cells along Trichoplax’s periphery that she thinks may help herd the cilia by secreting a chemical signal that makes them pause. The chemicals are similar to the neurotransmitters that regulate appetite and contractions of the digestive tract in humans, according to the neurobiologist Diego Bohórquez, of Duke University. When many animals are grouped together, a single Trichoplax releasing the chemical can trigger its neighbors to secrete as well, causing the whole group to slow down and graze on algae “much like bison on a grassy plain in Yellowstone,” Borhórquez wrote in a 2018 article in the scientific journal Brain Research.The Feywild represents the intrinsic power of nature: its wildness and beauty, its chaos and unscrupulous dangers. Denizens of the Plane of Faerie can be equally imposing. Even the weakestamong them can create dimensional rifts. The strongest collect knowledge and power over their long lives and don’t part with any of it for free. Use joints, bones and muscles to build creatures that are only limited by your imagination. Watch how the combination of a neural network and a genetic algorithm can enable your creatures to "learn" and improve at their given tasks all on their own. A coven consists of three hags so that any arguments between two hags can be settled by the third. If more than three hags ever come together, as might happen if two covens come into conflict, the result is usually chaos. Night hag: Once creatures of the Feywild, night hags were exiled to Hades. These creatures befoul all good things, turning love into obsession and generosity to selfishness. W hen Prakash and his team reach Monterey, a red tide caused by billions of plankton has turned the water so dark that it looks like obsidian. Crouching in the sheltered harbor of the Monterey marina beside a sailboat christened Diablito, Prakash slides his arm elbow deep into the water and draws up a length of fishing line. This time, the trap is intact.

When hags must work together, they form covens, in spite of their selfish natures. A coven is made up of hags of any type, all of whom are equals within the group. However, each of the hags continues to desire more personal power.Shared Spellcasting.While all three members of a hag coven are within 30 feet of one another, they can each cast the following spells from the wizard’s spell list but must share the spell slots among themselves: Like Trichoplax, Prakash and his 15 to 20 graduate students, postdocs, and lab technicians seem to move in a thousand directions at once. One day I watched as Prakash taught a new doctoral student, Hannah Rosen, how to suction Trichoplax out of a petri dish full of seawater and settle them on a slide. Move too slowly, and the animal will attach itself stubbornly to the syringe, Prakash explained, his hand darting toward the slide with the speed and precision of a heron’s beak. To prevent Trichoplax from creeping off the slides, Prakash has built a small well out of double-sided tape, which he calls a jail. “For the first 30 designs we made, it figured out how to break out of the jail,” he said, with obvious fondness. “It can slip under even the tiniest of gaps. It’s quite remarkable.”