The How and Why of Ultravision
For those old enough to have played in the early years of 1st Edition Dungeons & Dragons, there was a type of vision called ultravision. Ultravision was on the opposite end of the spectrum from infravision, which was the ability to see into the infrared, or in other words, heat. As expected, ultravision allowed seeing into the other extreme, the ultraviolet range. Very few creatures possessed the ability (and absolutely no player races did either), so it was a rarity to come across in the game. Many players felt it was poorly explained and amounted to little other than a different kind of infravision, so slowly it fell out of use until 3E, where it was expunged completely.
Endless Blue 