Tagnihi
Deep in the mystical forest of Pulau Cemara, there are shadowed meadows filled with dancing, multi-colored lights. These lights are created by the Tagnihi - small, glowing insects that are said to predict the future.
Tagnihi are soft-bodied beetle-like insects that can grow up to an inch long. They have the ability to glow in many colors, and use this glow to coordinate with each other. They exhibit hive-like behavior, and those who have studied them claim that the individual insects are in constant communication with each other, and that their light-based communication allows the hive to operate as a single organism. They live exclusively in the deepest parts of the Pulau Cemara, in places where the canopy is so thick that the ground is in perpetual twilight. They are omnivores, hunting other insects that live in the forest as well as the plants that grow there. Some people claim that the Tagnihi actually cultivate other, smaller insects for food, protecting them from predators and carrying them from plant to plant. It is also said that they have a great hatred of spiders, and there are never any spiders or spiderwebs found in the meadows of the Tagnihi.
The most intriguing thing about these creatures is their apparent ability to perceive the future, and to foretell it to those who know how to read their messages. They say that it is impossible to capture a Tagnihi, and that if you go into the forest with that intent, you will simply never find one. Alternatively, those who go seeking to harm the forest may see the lights in the distance, but following towards them will lead them into one peril after another, usually ending in an encounter with the Enkantado who guard the forest. But if you enter the Pulau Cemara with a peaceful heart and an offering for the Tagnihi, following their lights will bring you to one of the meadows, and there you will be granted a prophecy.
The offering to the Tagnihi is typically one of fruit, although other food items can also please them, especially something sweet like honey. When you enter the meadow of the Tagnihi, you must place the offering on the ground in the center of the meadow, and then back away to sit quietly at the edge. There, you should focus on the question you wish the Tagnihi to answer. If the offering is accepted, the hive will descend upon it, gorging themselves on the food. Then they will arise in a cloud, and the prophecy will begin.
The Tagnihi will dance, creating patterns of swirling and shifting colors in the air. Learning to read these patterns is a difficult art that takes many years, but once mastered, the patterns accurately predict future events. The viewer must relax their gaze and try to see the pattern in its entirety and not try to focus on any single part in order to grasp the message conveyed. The Tagnihi will answer the question foremost in the mind of the person who laid down the offering while they feasted. The prophecy will vary in specificity based on the question - short-term simple questions will receive definitive and detailed answers, while broader and longer-term questions get much vaguer responses. For example, if you ask whether you will survive a particular journey you intend to take tomorrow, the Taghini may give a clear yes or no (with details of what may happen). On the other hand, if you ask about what your life will be like if you marry one person over another, the answer will reflect how broad the range of possibilities are.
Those who seek a prophecy should seek a Tagtuwaan, someone who has studied and learned the art of reading the dance of the Tagnihi. Tagtuawaan are always of the Tau Tanah ethnicity, and are rare on Lahat since the conquest by the Mekongga. They will guide the questioner in the process of acquiring the prophecy, and interpret the Taghini's answer.
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These remind me of fairies, especially with their love of fruit and their ability to foretell the future. (I like that you didn't just make fairies, though.) I particularly like the details how complicated the prophecies can be, especially if you're asking about something further in the future that could be affected by many things. I also like that they don't like spiders because I don't either. I'd love to know more about how they keep spiders away from their part of the forest. Do they eat them? fight them? Do they just grow so much eucalyptus and peppermint that the spiders want nothing to do with them?
I haven't decided for sure, but I think they kill off any spiders that invade their territory. The Tagnihi are larger than most spiders, and operate collectively, so I think they can hunt down and eliminate any spiders that they object to.