Arcweom eggs can only be found in places with an exceptionally high concentration of magic. The transformation into a fully-grown Arcweom begins when an egg amasses enough ambient magic to sustain its growth.
Arcweoms are magical adepts able to intuitively work magics that might take other beings years of study and practice to master. The runes that glow upon their scales shift and twist, creating themselves anew with each spell the Arcweom casts. The gem that hangs suspended between an Arcweom’s horns acts both as a focus for casting and a storehouse of excess magical energy.
Arcweoms have always been regarded with awe and a certain amount of reverence, if not outright worship, from non-spell casters.