Luminous Hallows

Description: The Luminous Hallows is a strange place, stretching out quite far beneath the Evernight Forest. There are only a few openings to it and once inside you'll arrive about a hundred meters below the ground. Within, the ceiling of the cavern is so high and the walls spread so far apart, that it's difficult to tell if you're actually underground. Ironically, while the forest above is pitch dark, the underground is surprisingly more lit. Growing here are odd bioluminescent plants including trees with leaves that glow with a wide spectrum of colors- mostly purples, reds and blues. Often the ceiling of the cave, which stretches sometimes hundreds of feet up, is covered with many upon many glowing flowers. Due to this, some mistakenly judge that they've made it back to the surface in the forest above. Despite the mild visibility for those without perfect night vision, the properties of the darkness are unaffected by the kind of light produced by the illumination-producing plants. Therefore creatures such as shadow fish can swim around freely without 'drowning' in the light. Also, those sensitive to light such as the creatures native to the forest aren't negatively affected by the light- those reasoning that this would be a safe haven from the creatures dwelling here would be sadly mistaken. Another odd property of the plants is that they can't survive in normal light; even a little exposure will often be enough to cause them to wither slightly. Obviously this is why they're only found deep underground, where there is almost no chance of light reaching them. The more knowledgeable explorers know to bring flashlights or light-producing spells to ward off the more carnivorous species. A large river system runs through parts of the cave, the plants within causing the water to light up, giving the water it's self bioluminisent, the waterfalls spread through the hallows that travel down into a large underground lake are a magnificent sight to behold. Merfolk who live in these waters usually have very pale white or bluish coloration. This is because they live much deeper, beyond where even the luminescent plants grow. Due to their environment, they mostly have limited vision or even blindness. However, they are very attuned to slightest vibrations, originating from within the water or not. Even if adventurers think that staying clear of the water will keep them safe from what predators may be in it, the merfolk can simply slide onto land to intercept prey. Though they're still fairly clumsy on land, they are often able to catch prey by surprise. Dryads living here are usually fairly shorter than those on the surface. The colorful-glowing plants of the area grow on and around them in a uniquely decorating fashion. To an extent they can control the glowing of the plants, at times dimming and brightening them to attract prey. Many more dryads of the underground are the wandering sort rather than primarily staying rooted down to one spot as most dryads are known for. This area is very well known for the dridder population, many of which have bioluminescent patterns on their abdomens. Chilotaurs are also numerous here, along with other varieties of insect hybrids that may differ from their above-ground counterparts in a similar manner- physical differences noted among Luminous Hallows populations is dridders possessing multiple eyes and chilotaurs having more insect-like features. 
Unique Fauna and Flora: 
Tentacle Orb
Size: 5-10 ft
Threat: Low
A strange totally round creature that possess similar abilities to shadow fish. They float slowly through pitch-black areas. While light doesn't kill them, it does cause them to drop to the ground. They are relatively harmless to humans, but will occasionally frighten a passerby if they bump into one floating in the dark. The way they feed is much like a jellyfish, possessing 2-6 tentacle-like appendages that are usually stored within its body. If it senses movement of nearby potential prey- mostly birds, insects and currently small fairies- the tentacles will emerge, moving surprisingly fast to snatch its target up. The tentacles deliver a nasty paralyzing venom to subdue the prey while they consume it. Stings to humans by smaller ones are rare, while larger ones are known to occasionally eat humans.
Moseura
Size: 3 inches
Threat: Very Low
Easily mistaken at first for fairies, they are in fact a more insect-like creature. They are resistant to magic with a few magical abilities themselves. They possess a limited intelligence, which is best described as childlike. They appear to be unrelated to Felaryan fairies, possessing a moth-like appearance. They often travel in groups of 3-5 but may be seen in groups of about thirty and normally not many more. Their diet appears to consist of plant matter, including berries and fruits.
A common prey species, they have developed a survival tactic through what little magic is available to them. This is to let loose a strong flash of light-based magic which brightens a small area for a short amount of time. This hopefully stuns an attacker unfamiliar with strong light. When they are in even bigger groups, this tactic can create even larger flashes. With rare truly massive groups, the flash is blinding even to those far away. They also use this flashing to communicate over distances, a code that only they seem to be able to understand. They tend to get along well with tinies, humans and even some dusk nymphs that share the same territory.
Burrower
Size: 30 ft long
Threat: Low
A long, segmented insectoid creature that burrows beneath the ground and can be seen as a travelling bulge just below the surface, which may give someone a scare should they see it going about its business. Their appearance is similar to that of the frightening tonorions, though they are only distantly related. Burrowers are not a great threat to humans as they instead prey on smaller creatures.
Creeping Weed
Size: 8 ft
Threat: Medium
A carnivorous plant which grows primarily throughout the caverns of Luminous Hallows. It looks like an octopus of sorts with a large bulbous 'head', a bit inflated, which is around 8ft wide on average with vine-like tendrils attached to it in varying amounts and length; 10-12 tendrils of 22- 30 feet in length.
It slowly crawls across the ground with its vine-like appendages, creeping silently to sneak up on unsuspecting prey. Its hunting method is simply to lay flat on the ground until it picks up the vibrations of something nearby; once determined to be the right size it begins creeping up to it steadily. When its target is reached it snatches them in tangles of vines, pulling them into the mouth-like opening on its bulb's underside where strong muscles clamp shut to prevent escape. Its prey mostly consists of human-sized creatures and it even attempts to snag creatures such as fairies by sensing just their wing vibrations. They seem to be somewhat intelligent, as a learned behavior demonstrated is to damage a fairy's wings before ingesting it so it can't escape.