Tenebrium Steel

Tenebrium steel is a magecrafted steel alloy. It is often dark in color, and never reflective even when finely smoothed. Mechanically, tenebrium is very durable and when fashioned in blades, it can hold its edge indefinitely.
It's most noteworthy feature however, is that it is invisivle to all kinds of supernatural sights and sensors such as the ones produced by effects like the clairvoyance and scying spells. Containers made of tenebrium steel also render their contents invisible to such sensors.
Objects made of tenebrium can only be seen with naked eyes. Furthermore, even when enchanted with magic, tenebrium steel registers as non-magical, making tenebrium-made weapons ideal for use by assassins.
It is believed that tenebrium also bars the supernatural cosmic sight deities use to observe remote locations. If this is true, then a deity would be unable to eavesdrop a conversation made by mortals within a tenebrium room. For that matter, the deity would be incapable of even sensing the existence of such a room unless it had an avatar standing right outside of it.

Type

Metal

Color

Varies, but always dark and non-reflective