Trelons do not like natural light, and torches or strong lanterns can prevent a trelon from attacking its target. Light sorceries, however, drive them into frenzies, and they attack any opponent using them without hesitation.
Combat: A trelon swarm is terrible to behold. When they appear, they mob any nearby creature, tearing through their victims like scythes. Trelons attack with their two armspikes, bisecting a target like a pair of cutting shears.
Trelons never “appear” at distances greater than 30 feet from their victim. Until a victim comes within range, the trelons simply don’t exist. A target might never even know that he or she is in the middle of a swarm of trelons until they suddenly begin to materialize, imposing a -3 penalty to their prey’s surprise roll. Where these creatures come from is unknown, but they seem to appear only in shadowy conditions where there is no natural light. It is not known where they retreat to once they have finished their attack.
No one knows how these creatures hunt. Some believe that the trelons track a creature by its spellcasting, its shadow, its emotions, or its sound. It is known that trelons have the ability to track a victim through almost any spell or magical item designed to cloak the victim. They are drawn to invisibility, dust of disappearance, displacements, and shadow magic. Trelons can sense a target no matter how well they are hidden. It has been observed (under extremely bloody circumstances) that magical cloaking effects seem to drive trelons into a rage, and they prefer to attack any invisible or cloaked target in range.
Trelons are immune to hold monster, protection from evil, illusions, shadow magic, and mind-influencing spells.
Habitat/Society: Trelons speak in soft clicks and chittering noises, which rise to a near-deafening screeching when they strike. Their insect nature makes several sages suspect that they may have a hive mentality, but like much that is known about trelons, it is only speculation.
Can we modify the light sensitivity so that when they are exposed to full sunlight or some sort of powerful light they rage like a barbarian and want to destroy what is attacking them.
LIght sources would bug them , give them a penalty for that.
The problem with shadow walk is that it deposits you a random distance from your intended destination. In a scope of miles. It's more like teleport than ethereal jaunt.