Filimon

The filimon is a type of monitor lizard, about four feet long as an adult and knee high. They have snake-like scales that can range from mocha brown to olive green to saffron yellow. As carnivores, they primarily eat small rodents and fish, often hunting in the Wandering Wilds when the terrain suits them, but have also been known to wander onto farms and into towns in search of food.   The filimon is most famous for its magically enhanced, impenetrable skin. As juveniles, the filimon are just as vulnerable as any other lizard, but when they reach maturity, they naturally seek out a magical tree called haligould, known for causing paralysis among humans. Filimon claw at the base of the tree until sap is released. Before they bathe in it, the filimon salivates into the pooling sap, causing the mixture to congeal. As they roll around, it attaches to their skin and hardens, creating an impenetrable outer shield. This layer cannot be pierced, cut, or burned, and thus is very highly prized by soldiers for armor, shields, and construction.
Because the skin is so protective, it is extremely difficult to kill a filimon. Luckily, when filimon molt, they shed their skin. A milky substance is secreted on the underside of their body and dissolves the layer away. The skin falls off within a day or two, once the substance has weakened the legs. Sheets of this protective layer, called “filly,” are frequently found in areas where filimon reside, but occasionally pieces of leg-sections can be found as well.
The most common way to penetrate filly is with the milky substance they use prior to molting (weapons may sometimes be coated in it, but it is extremely hard to obtain). Both for this substance and for their skins, filimon are a common livestock. The saliva is also harvested, primarily as a cooking thickener, but is not as nearly as profitable as the other two.
But filimon are not easy to keep. They are aggressive, so must be kept away from other kinds of livestock, plus the harigould sap required to make the filly must be safely handled.
A point, whether magic or not, will not pierce a filimon. But filimon are not impervious to magic. As long as the magic is meant to break the filly layer, it will face no hindrance. Filimon can be fed magical substances, and runes can certainly take hold (though they are easily wiped off).